new file mode 100644
@@ -0,0 +1,299 @@
+From a023e4192dbbdc7d8d6b391ef9b226c2cfffe97e Mon Sep 17 00:00:00 2001
+From: tomasilluminati <tomas.illuminati@owasp.org>
+Date: Sun, 19 Apr 2026 05:57:33 -0300
+Subject: [PATCH] (fix): denial of service in twisted.names mitigation
+
+CVE: CVE-2026-42304
+Upstream-Status: Backport [https://github.com/twisted/twisted/commit/be71ecaa113f642f03083bd5ed33af47c59308c8]
+
+(cherry picked from commit be71ecaa113f642f03083bd5ed33af47c59308c8)
+Signed-off-by: Hetvi Thakar <hthakar@cisco.com>
+---
+ src/twisted/names/dns.py | 116 +++++++++++++++++++++++++----
+ src/twisted/names/test/test_dns.py | 91 ++++++++++++++++++++++
+ 2 files changed, 193 insertions(+), 14 deletions(-)
+
+diff --git a/src/twisted/names/dns.py b/src/twisted/names/dns.py
+index c7644ef50..7142d9e75 100644
+--- a/src/twisted/names/dns.py
++++ b/src/twisted/names/dns.py
+@@ -11,6 +11,7 @@ Future Plans:
+ from __future__ import annotations
+
+ # System imports
++import contextvars
+ import inspect
+ import random
+ import socket
+@@ -126,6 +127,7 @@ __all__ = [
+ "OP_UPDATE",
+ "PORT",
+ "AuthoritativeDomainError",
++ "DNSDecodeError",
+ "DNSQueryTimeoutError",
+ "DomainError",
+ ]
+@@ -444,6 +446,64 @@ def readPrecisely(file, l):
+ return buff
+
+
++# Cap the total number of compression-pointer dereferences performed while
++# decoding a single DNS message. A hostile peer can otherwise craft a packet
++# in which every record name chases a long compression chain, forcing O(N*M)
++# work and stalling the reactor.
++MAX_COMPRESSION_POINTERS_PER_MESSAGE = 1000
++
++
++class DNSDecodeError(ValueError):
++ """
++ Raised when a DNS message cannot be decoded because it violates a
++ protocol-level safety limit
++ """
++
++
++class _DecodeContext:
++ """
++ Mutable state shared between the L{IEncodable} decoders invoked while
++ reading a single DNS message.
++
++ The primary purpose is to bound the total number of compression-pointer
++ jumps taken across every name in the message, defending against packets
++ that fan out thousands of records pointing to deeply chained pointers.
++
++ @ivar jumps: The number of compression pointers followed so far.
++ @ivar maxJumps: The inclusive upper bound on C{jumps}. Exceeding it
++ causes L{registerJump} to raise L{DNSDecodeError}.
++ """
++
++ __slots__ = ("jumps", "maxJumps")
++
++ def __init__(self, maxJumps: int = MAX_COMPRESSION_POINTERS_PER_MESSAGE) -> None:
++ self.jumps = 0
++ self.maxJumps = maxJumps
++
++ def registerJump(self) -> None:
++ """
++ Record that a compression pointer has been followed
++
++ @raise DNSDecodeError: if the cumulative number of jumps exceeds
++ L{maxJumps}
++ """
++ self.jumps += 1
++ if self.jumps > self.maxJumps:
++ raise DNSDecodeError(
++ "Too many compression pointers while decoding DNS message "
++ f"(limit is {self.maxJumps})"
++ )
++
++
++# Tracks state across nested calls without altering every record's signature.
++# L{Message.decode} manages the lifecycle per-message, while standalone decoders
++# default to a local context when C{_decodeContextVar} is C{None}
++
++_decodeContextVar: contextvars.ContextVar[_DecodeContext | None] = (
++ contextvars.ContextVar("_dnsDecodeContext", default=None)
++)
++
++
+ class IEncodable(Interface):
+ """
+ Interface for something which can be encoded to and decoded
+@@ -591,7 +651,7 @@ class Name:
+ strio.write(label)
+ strio.write(b"\x00")
+
+- def decode(self, strio, length=None):
++ def decode(self, strio, length=None, context=None):
+ """
+ Decode a byte string into this Name.
+
+@@ -599,12 +659,27 @@ class Name:
+ @param strio: Bytes will be read from this file until the full Name
+ is decoded.
+
++ @type context: L{_DecodeContext} or L{None}
++ @param context: Shared decoding state used to cap the total number
++ of compression-pointer jumps taken while decoding the enclosing
++ DNS message. When L{None}, the context installed by
++ L{Message.decode} is used if one is active; otherwise a fresh,
++ call-local context is created so that direct callers remain
++ protected and backwards compatible.
++
+ @raise EOFError: Raised when there are not enough bytes available
+ from C{strio}.
+
+- @raise ValueError: Raised when the name cannot be decoded (for example,
+- because it contains a loop).
++ @raise ValueError: Raised when the name cannot be decoded because it
++ contains a compression loop.
++
++ @raise DNSDecodeError: Raised when the cumulative number of
++ compression-pointer jumps exceeds the configured limit.
+ """
++ if context is None:
++ context = _decodeContextVar.get()
++ if context is None:
++ context = _DecodeContext()
+ visited = set()
+ self.name = b""
+ off = 0
+@@ -616,6 +691,7 @@ class Name:
+ return
+ if (l >> 6) == 3:
+ new_off = (l & 63) << 8 | ord(readPrecisely(strio, 1))
++ context.registerJump()
+ if new_off in visited:
+ raise ValueError("Compression loop in encoded name")
+ visited.add(new_off)
+@@ -2704,19 +2780,31 @@ class Message(tputil.FancyEqMixin):
+ self.checkingDisabled = (byte4 >> 4) & 1
+ self.rCode = byte4 & 0xF
+
+- self.queries = []
+- for i in range(nqueries):
+- q = Query()
+- try:
+- q.decode(strio)
+- except EOFError:
+- return
+- self.queries.append(q)
++ # A single shared counter bounds the total compression-pointer work
++ # performed across every name in this message. It is installed on
++ # the context variable so nested record decoders pick it up without
++ # needing to thread it through each signature.
++ token = _decodeContextVar.set(_DecodeContext())
++ try:
++ self.queries = []
++ for i in range(nqueries):
++ q = Query()
++ try:
++ q.decode(strio)
++ except EOFError:
++ return
++ self.queries.append(q)
+
+- items = ((self.answers, nans), (self.authority, nns), (self.additional, nadd))
++ items = (
++ (self.answers, nans),
++ (self.authority, nns),
++ (self.additional, nadd),
++ )
+
+- for l, n in items:
+- self.parseRecords(l, n, strio)
++ for l, n in items:
++ self.parseRecords(l, n, strio)
++ finally:
++ _decodeContextVar.reset(token)
+
+ def parseRecords(self, list, num, strio):
+ for i in range(num):
+diff --git a/src/twisted/names/test/test_dns.py b/src/twisted/names/test/test_dns.py
+index 3b8f6e130..9b27c4b3a 100644
+--- a/src/twisted/names/test/test_dns.py
++++ b/src/twisted/names/test/test_dns.py
+@@ -352,6 +352,60 @@ class NameTests(unittest.TestCase):
+ stream = BytesIO(b"\xc0\x00")
+ self.assertRaises(ValueError, name.decode, stream)
+
++ def test_rejectTooManyCompressionPointers(self):
++ """
++ L{Name.decode} raises L{dns.DNSDecodeError} when the number of
++ compression-pointer dereferences taken for a single message exceeds
++ the limit carried by the shared L{dns._DecodeContext}.
++ """
++ # Five distinct pointers chained end-to-end, terminated by a zero
++ # label byte. With a maxJumps of three the fourth dereference must
++ # trip the safety limit.
++ payload = b"\xc0\x02\xc0\x04\xc0\x06\xc0\x08\x00"
++ context = dns._DecodeContext(maxJumps=3)
++ self.assertRaises(
++ dns.DNSDecodeError,
++ dns.Name().decode,
++ BytesIO(payload),
++ None,
++ context,
++ )
++
++ def test_compressionPointerCounterIsShared(self):
++ """
++ The L{dns._DecodeContext} counter accumulates across successive
++ L{Name.decode} calls, so that a message whose individual names are
++ each within bounds is still rejected when their aggregate exceeds
++ the configured limit.
++ """
++ payload = b"\xc0\x02\xc0\x04\x00"
++ context = dns._DecodeContext(maxJumps=3)
++
++ stream = BytesIO(payload)
++ dns.Name().decode(stream, context=context)
++ self.assertEqual(context.jumps, 2)
++
++ stream.seek(0)
++ self.assertRaises(
++ dns.DNSDecodeError,
++ dns.Name().decode,
++ stream,
++ None,
++ context,
++ )
++
++ def test_decodeWithoutContextIsBackwardsCompatible(self):
++ """
++ L{Name.decode} continues to work when called without a context,
++ using a fresh per-call counter so existing callers are unaffected.
++ """
++ name = dns.Name()
++ stream = BytesIO()
++ dns.Name(b"example.org").encode(stream)
++ stream.seek(0)
++ name.decode(stream)
++ self.assertEqual(name.name, b"example.org")
++
+ def test_equality(self):
+ """
+ L{Name} instances are equal as long as they have the same value for
+@@ -761,6 +815,43 @@ class MessageTests(unittest.SynchronousTestCase):
+ """
+ self.assertEqual(dns.Message().authenticData, 0)
+
++ def test_rejectCompressionPointerFlood(self):
++ """
++ L{Message.decode} installs a shared compression-pointer counter and
++ raises L{dns.DNSDecodeError} when the aggregate number of pointer
++ dereferences across every record in the message exceeds
++ L{dns.MAX_COMPRESSION_POINTERS_PER_MESSAGE}.
++ """
++ chainLength = 100
++ numRecords = 8000
++ header = struct.pack(
++ "!H2B4H", 0x1234, 0x80, 0x00, 0, numRecords, 0, 0
++ )
++
++ # Long compression chain inside the RDATA of an unknown
++ # record so that subsequent records can aim pointers at it.
++ owner = b"\x04rrrr\x00"
++ chainBase = len(header) + len(owner) + 10
++ chain = bytearray()
++ for i in range(chainLength):
++ chain += struct.pack("!H", 0xC000 | (chainBase + 2 * (i + 1)))
++ chain += b"\x04test\x00"
++
++ firstRecord = (
++ owner
++ + struct.pack("!HHIH", 999, 1, 0, len(chain))
++ + bytes(chain)
++ )
++ followupRecord = (
++ struct.pack("!H", 0xC000 | chainBase)
++ + struct.pack("!HHIH", 1, 1, 0, 4)
++ + b"\x00\x00\x00\x00"
++ )
++ payload = header + firstRecord + followupRecord * (numRecords - 1)
++
++ message = dns.Message()
++ self.assertRaises(dns.DNSDecodeError, message.decode, BytesIO(payload))
++
+ def test_authenticDataOverride(self):
+ """
+ L{dns.Message.__init__} accepts a C{authenticData} argument which
new file mode 100644
@@ -0,0 +1,30 @@
+From 094d33d4073368ab1a85fcf63e3b75addb01fd6a Mon Sep 17 00:00:00 2001
+From: Tomas Illuminati Balbin <dev@tomasilluminati.com>
+Date: Mon, 20 Apr 2026 09:17:13 -0300
+Subject: [PATCH] Update src/twisted/names/dns.py
+
+Co-authored-by: Adi Roiban <adiroiban@gmail.com>
+
+CVE: CVE-2026-42304
+Upstream-Status: Backport [https://github.com/twisted/twisted/commit/86e1b5490de5baa8ca284d1e6f4f0ade3e8ad7e0]
+
+(cherry picked from commit 86e1b5490de5baa8ca284d1e6f4f0ade3e8ad7e0)
+Signed-off-by: Hetvi Thakar <hthakar@cisco.com>
+---
+ src/twisted/names/dns.py | 3 +--
+ 1 file changed, 1 insertion(+), 2 deletions(-)
+
+diff --git a/src/twisted/names/dns.py b/src/twisted/names/dns.py
+index 7142d9e75..93e4080bf 100644
+--- a/src/twisted/names/dns.py
++++ b/src/twisted/names/dns.py
+@@ -2784,8 +2784,7 @@ class Message(tputil.FancyEqMixin):
+ # performed across every name in this message. It is installed on
+ # the context variable so nested record decoders pick it up without
+ # needing to thread it through each signature.
+- token = _decodeContextVar.set(_DecodeContext())
+- try:
++ with _decodeContextVar.set(_DecodeContext()):
+ self.queries = []
+ for i in range(nqueries):
+ q = Query()
new file mode 100644
@@ -0,0 +1,33 @@
+From 7213b262b9c98fe6d522dbd23fd83bb9535b54c6 Mon Sep 17 00:00:00 2001
+From: Tomas Illuminati Balbin <dev@tomasilluminati.com>
+Date: Mon, 20 Apr 2026 09:18:05 -0300
+Subject: [PATCH] Update src/twisted/names/test/test_dns.py
+
+Co-authored-by: Adi Roiban <adiroiban@gmail.com>
+
+CVE: CVE-2026-42304
+Upstream-Status: Backport [https://github.com/twisted/twisted/commit/c75d44ed81b47f8086ed801cfcdb2568b0b32301]
+
+(cherry picked from commit c75d44ed81b47f8086ed801cfcdb2568b0b32301)
+Signed-off-by: Hetvi Thakar <hthakar@cisco.com>
+---
+ src/twisted/names/test/test_dns.py | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/src/twisted/names/test/test_dns.py b/src/twisted/names/test/test_dns.py
+index 9b27c4b3a..94aa4a802 100644
+--- a/src/twisted/names/test/test_dns.py
++++ b/src/twisted/names/test/test_dns.py
+@@ -389,9 +389,9 @@ class NameTests(unittest.TestCase):
+ self.assertRaises(
+ dns.DNSDecodeError,
+ dns.Name().decode,
+- stream,
+- None,
+- context,
++ strio=stream,
++ length=None,
++ context=context,
+ )
+
+ def test_decodeWithoutContextIsBackwardsCompatible(self):
new file mode 100644
@@ -0,0 +1,318 @@
+From 3cb501679cd7f45ab49d32cf72ec546ef3a64825 Mon Sep 17 00:00:00 2001
+From: Tomas Illuminati <tomas.illuminati@owasp.org>
+Date: Mon, 20 Apr 2026 10:01:39 -0300
+Subject: [PATCH] names: Refactor DNS compression mitigation
+
+CVE: CVE-2026-42304
+Upstream-Status: Backport [https://github.com/twisted/twisted/commit/d7d81e08d46b3f266963ea77e5f6b4a333af455f]
+
+Backport Changes:
+- Adapted the 25.5.0 imports by moving Sequence from typing to
+ collections.abc and retaining the target's Optional and Union imports.
+
+(cherry picked from commit d7d81e08d46b3f266963ea77e5f6b4a333af455f)
+Signed-off-by: Hetvi Thakar <hthakar@cisco.com>
+---
+ src/twisted/names/dns.py | 113 +++++++++++++------
+ src/twisted/names/newsfragments/12626.bugfix | 1 +
+ src/twisted/names/test/test_dns.py | 47 ++++----
+ 3 files changed, 105 insertions(+), 56 deletions(-)
+ create mode 100644 src/twisted/names/newsfragments/12626.bugfix
+
+diff --git a/src/twisted/names/dns.py b/src/twisted/names/dns.py
+index 93e4080bf..869ffec76 100644
+--- a/src/twisted/names/dns.py
++++ b/src/twisted/names/dns.py
+@@ -16,9 +16,11 @@ import inspect
+ import random
+ import socket
+ import struct
++from collections.abc import Sequence
++from contextlib import contextmanager
+ from io import BytesIO
+ from itertools import chain
+-from typing import Optional, Sequence, SupportsInt, Union, overload
++from typing import Final, Optional, SupportsInt, Union, overload
+
+ from zope.interface import Attribute, Interface, implementer
+
+@@ -446,17 +448,19 @@ def readPrecisely(file, l):
+ return buff
+
+
+-# Cap the total number of compression-pointer dereferences performed while
+-# decoding a single DNS message. A hostile peer can otherwise craft a packet
+-# in which every record name chases a long compression chain, forcing O(N*M)
+-# work and stalling the reactor.
+-MAX_COMPRESSION_POINTERS_PER_MESSAGE = 1000
++MAX_COMPRESSION_POINTERS_PER_MESSAGE: Final = 1000
++"""
++Cap the total number of compression-pointer dereferences performed while
++decoding a single DNS message. A hostile peer can otherwise craft a packet
++in which every record name chases a long compression chain, forcing
++C{O(N*M)} work and stalling the reactor.
++"""
+
+
+ class DNSDecodeError(ValueError):
+ """
+ Raised when a DNS message cannot be decoded because it violates a
+- protocol-level safety limit
++ protocol-level safety limit.
+ """
+
+
+@@ -469,8 +473,12 @@ class _DecodeContext:
+ jumps taken across every name in the message, defending against packets
+ that fan out thousands of records pointing to deeply chained pointers.
+
++ This class is private. External callers must not rely on it; the
++ per-message scope is installed and torn down by L{Message.decode}
++ through L{_decodeContextVar}.
++
+ @ivar jumps: The number of compression pointers followed so far.
+- @ivar maxJumps: The inclusive upper bound on C{jumps}. Exceeding it
++ @ivar maxJumps: The inclusive upper bound on L{jumps}. Exceeding it
+ causes L{registerJump} to raise L{DNSDecodeError}.
+ """
+
+@@ -482,10 +490,14 @@ class _DecodeContext:
+
+ def registerJump(self) -> None:
+ """
+- Record that a compression pointer has been followed
++ Record that a compression pointer has been followed.
++
++ The check is performed before any further bytes are read so the
++ caller fails fast as soon as the aggregate limit is breached, even
++ if additional records remain in the buffer.
+
+ @raise DNSDecodeError: if the cumulative number of jumps exceeds
+- L{maxJumps}
++ L{maxJumps}.
+ """
+ self.jumps += 1
+ if self.jumps > self.maxJumps:
+@@ -495,15 +507,37 @@ class _DecodeContext:
+ )
+
+
+-# Tracks state across nested calls without altering every record's signature.
+-# L{Message.decode} manages the lifecycle per-message, while standalone decoders
+-# default to a local context when C{_decodeContextVar} is C{None}
+-
++# Private module-level L{contextvars.ContextVar} used to share a single
++# L{_DecodeContext} across the re-entrant calls performed while decoding one
++# DNS message. L{contextvars} (rather than a plain module attribute) is used
++# on purpose: although Twisted's reactor is single-threaded, message decoding
++# is re-entrant across many records in a single pass and L{ContextVar}
++# guarantees the scope is restored correctly on exit -- and remains isolated
++# per-task should a future caller decode messages from multiple
++# L{asyncio}-style contexts concurrently.
+ _decodeContextVar: contextvars.ContextVar[_DecodeContext | None] = (
+ contextvars.ContextVar("_dnsDecodeContext", default=None)
+ )
+
+
++@contextmanager
++def _installDecodeContext(context: _DecodeContext):
++ """
++ Install C{context} on L{_decodeContextVar} for the duration of the
++ C{with} block and restore the previous value on exit.
++
++ This wraps the L{contextvars.ContextVar.set} / L{contextvars.ContextVar.reset}
++ token dance so call sites can use a plain C{with} statement.
++
++ @param context: The L{_DecodeContext} to install as the active context.
++ """
++ token = _decodeContextVar.set(context)
++ try:
++ yield context
++ finally:
++ _decodeContextVar.reset(token)
++
++
+ class IEncodable(Interface):
+ """
+ Interface for something which can be encoded to and decoded
+@@ -609,8 +643,18 @@ class Name:
+
+ @ivar name: A byte string giving the name.
+ @type name: L{bytes}
++
++ @cvar maxCompressionPointers: Per-message cap on the total number of
++ compression-pointer dereferences L{decode} will follow before
++ raising L{DNSDecodeError}. Defined as a class attribute so
++ subclasses (and, in the future, individual instances) may override
++ it to tune the trade-off between tolerance for legitimately
++ verbose messages and resistance to denial-of-service attacks.
++ @type maxCompressionPointers: L{int}
+ """
+
++ maxCompressionPointers: int = MAX_COMPRESSION_POINTERS_PER_MESSAGE
++
+ def __init__(self, name: bytes | str = b""):
+ """
+ @param name: A name.
+@@ -651,35 +695,37 @@ class Name:
+ strio.write(label)
+ strio.write(b"\x00")
+
+- def decode(self, strio, length=None, context=None):
++ def decode(self, strio, length=None):
+ """
+ Decode a byte string into this Name.
+
++ When invoked from L{Message.decode}, a shared compression-pointer
++ counter is picked up transparently from the private
++ L{_decodeContextVar}. Standalone callers get a fresh per-call
++ counter seeded from L{maxCompressionPointers}, so existing code
++ keeps working unchanged while still being protected against
++ pathological inputs.
++
+ @type strio: file
+ @param strio: Bytes will be read from this file until the full Name
+- is decoded.
++ is decoded.
+
+- @type context: L{_DecodeContext} or L{None}
+- @param context: Shared decoding state used to cap the total number
+- of compression-pointer jumps taken while decoding the enclosing
+- DNS message. When L{None}, the context installed by
+- L{Message.decode} is used if one is active; otherwise a fresh,
+- call-local context is created so that direct callers remain
+- protected and backwards compatible.
++ @type length: L{int} or L{None}
++ @param length: Present for compatibility with the L{IEncodable}
++ interface; ignored by this decoder.
+
+ @raise EOFError: Raised when there are not enough bytes available
+- from C{strio}.
++ from C{strio}.
+
+- @raise ValueError: Raised when the name cannot be decoded because it
+- contains a compression loop.
++ @raise ValueError: Raised when the name cannot be decoded because
++ it contains a compression loop.
+
+ @raise DNSDecodeError: Raised when the cumulative number of
+ compression-pointer jumps exceeds the configured limit.
+ """
++ context = _decodeContextVar.get()
+ if context is None:
+- context = _decodeContextVar.get()
+- if context is None:
+- context = _DecodeContext()
++ context = _DecodeContext(maxJumps=self.maxCompressionPointers)
+ visited = set()
+ self.name = b""
+ off = 0
+@@ -2782,9 +2828,10 @@ class Message(tputil.FancyEqMixin):
+
+ # A single shared counter bounds the total compression-pointer work
+ # performed across every name in this message. It is installed on
+- # the context variable so nested record decoders pick it up without
+- # needing to thread it through each signature.
+- with _decodeContextVar.set(_DecodeContext()):
++ # the private context variable so nested record decoders pick it up
++ # without needing to thread it through each signature.
++ decodeContext = _DecodeContext(maxJumps=Name.maxCompressionPointers)
++ with _installDecodeContext(decodeContext):
+ self.queries = []
+ for i in range(nqueries):
+ q = Query()
+@@ -2802,8 +2849,6 @@ class Message(tputil.FancyEqMixin):
+
+ for l, n in items:
+ self.parseRecords(l, n, strio)
+- finally:
+- _decodeContextVar.reset(token)
+
+ def parseRecords(self, list, num, strio):
+ for i in range(num):
+diff --git a/src/twisted/names/newsfragments/12626.bugfix b/src/twisted/names/newsfragments/12626.bugfix
+new file mode 100644
+index 000000000..44896c3e5
+--- /dev/null
++++ b/src/twisted/names/newsfragments/12626.bugfix
+@@ -0,0 +1 @@
++twisted.names was fix for Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. CVE-REFERENCE HERE
+\ No newline at end of file
+diff --git a/src/twisted/names/test/test_dns.py b/src/twisted/names/test/test_dns.py
+index 94aa4a802..9626115ab 100644
+--- a/src/twisted/names/test/test_dns.py
++++ b/src/twisted/names/test/test_dns.py
+@@ -356,48 +356,51 @@ class NameTests(unittest.TestCase):
+ """
+ L{Name.decode} raises L{dns.DNSDecodeError} when the number of
+ compression-pointer dereferences taken for a single message exceeds
+- the limit carried by the shared L{dns._DecodeContext}.
++ the limit carried by the shared L{dns._DecodeContext} installed
++ through the private L{dns._decodeContextVar}.
+ """
+ # Five distinct pointers chained end-to-end, terminated by a zero
+ # label byte. With a maxJumps of three the fourth dereference must
+ # trip the safety limit.
+ payload = b"\xc0\x02\xc0\x04\xc0\x06\xc0\x08\x00"
+ context = dns._DecodeContext(maxJumps=3)
+- self.assertRaises(
+- dns.DNSDecodeError,
+- dns.Name().decode,
+- BytesIO(payload),
+- None,
+- context,
+- )
++ with dns._installDecodeContext(context):
++ self.assertRaises(
++ dns.DNSDecodeError,
++ dns.Name().decode,
++ BytesIO(payload),
++ )
+
+ def test_compressionPointerCounterIsShared(self):
+ """
+ The L{dns._DecodeContext} counter accumulates across successive
+ L{Name.decode} calls, so that a message whose individual names are
+ each within bounds is still rejected when their aggregate exceeds
+- the configured limit.
++ the configured limit. This mirrors production: L{Message.decode}
++ invokes L{Name.decode} many times against the same stream under one
++ shared context.
+ """
+ payload = b"\xc0\x02\xc0\x04\x00"
+ context = dns._DecodeContext(maxJumps=3)
+
+- stream = BytesIO(payload)
+- dns.Name().decode(stream, context=context)
+- self.assertEqual(context.jumps, 2)
++ with dns._installDecodeContext(context):
++ stream = BytesIO(payload)
++ dns.Name().decode(stream)
++ self.assertEqual(context.jumps, 2)
+
+- stream.seek(0)
+- self.assertRaises(
+- dns.DNSDecodeError,
+- dns.Name().decode,
+- strio=stream,
+- length=None,
+- context=context,
+- )
++ stream.seek(0)
++ self.assertRaises(
++ dns.DNSDecodeError,
++ dns.Name().decode,
++ stream,
++ )
+
+ def test_decodeWithoutContextIsBackwardsCompatible(self):
+ """
+- L{Name.decode} continues to work when called without a context,
+- using a fresh per-call counter so existing callers are unaffected.
++ L{Name.decode} continues to work when called with no active
++ L{dns._decodeContextVar}, using a fresh per-call counter seeded
++ from L{dns.Name.maxCompressionPointers} so existing callers are
++ unaffected.
+ """
+ name = dns.Name()
+ stream = BytesIO()
new file mode 100644
@@ -0,0 +1,218 @@
+From 4aa0fdb33f2a12db2d234754b9b03d74df8eaf9d Mon Sep 17 00:00:00 2001
+From: Tomas Illuminati <tomas.illuminati@owasp.org>
+Date: Tue, 21 Apr 2026 17:26:49 -0300
+Subject: [PATCH] names: fix changes
+
+CVE: CVE-2026-42304
+Upstream-Status: Backport [https://github.com/twisted/twisted/commit/9df6d960d3569751ebb5567093fe1d1d9f63ca54]
+
+Backport Changes:
+- Retained the 25.5.0 Optional and Union typing imports while removing
+ Final; Sequence remains sourced from collections.abc after p4.
+
+(cherry picked from commit 9df6d960d3569751ebb5567093fe1d1d9f63ca54)
+Signed-off-by: Hetvi Thakar <hthakar@cisco.com>
+---
+ src/twisted/names/dns.py | 37 +++++++------
+ src/twisted/names/test/test_dns.py | 85 +++++++++++++-----------------
+ 2 files changed, 56 insertions(+), 66 deletions(-)
+
+diff --git a/src/twisted/names/dns.py b/src/twisted/names/dns.py
+index 869ffec76..ca5079454 100644
+--- a/src/twisted/names/dns.py
++++ b/src/twisted/names/dns.py
+@@ -20,7 +20,7 @@ from collections.abc import Sequence
+ from contextlib import contextmanager
+ from io import BytesIO
+ from itertools import chain
+-from typing import Final, Optional, SupportsInt, Union, overload
++from typing import Optional, SupportsInt, Union, overload
+
+ from zope.interface import Attribute, Interface, implementer
+
+@@ -448,15 +448,6 @@ def readPrecisely(file, l):
+ return buff
+
+
+-MAX_COMPRESSION_POINTERS_PER_MESSAGE: Final = 1000
+-"""
+-Cap the total number of compression-pointer dereferences performed while
+-decoding a single DNS message. A hostile peer can otherwise craft a packet
+-in which every record name chases a long compression chain, forcing
+-C{O(N*M)} work and stalling the reactor.
+-"""
+-
+-
+ class DNSDecodeError(ValueError):
+ """
+ Raised when a DNS message cannot be decoded because it violates a
+@@ -484,7 +475,7 @@ class _DecodeContext:
+
+ __slots__ = ("jumps", "maxJumps")
+
+- def __init__(self, maxJumps: int = MAX_COMPRESSION_POINTERS_PER_MESSAGE) -> None:
++ def __init__(self, maxJumps: int = 1000) -> None:
+ self.jumps = 0
+ self.maxJumps = maxJumps
+
+@@ -644,16 +635,15 @@ class Name:
+ @ivar name: A byte string giving the name.
+ @type name: L{bytes}
+
+- @cvar maxCompressionPointers: Per-message cap on the total number of
++ @ivar maxCompressionPointers: Per-message cap on the total number of
+ compression-pointer dereferences L{decode} will follow before
+- raising L{DNSDecodeError}. Defined as a class attribute so
+- subclasses (and, in the future, individual instances) may override
+- it to tune the trade-off between tolerance for legitimately
+- verbose messages and resistance to denial-of-service attacks.
+- @type maxCompressionPointers: L{int}
++ raising L{DNSDecodeError}. Defaults to C{1000}. Override it on
++ a subclass or individual instance to tune the trade-off between
++ tolerance for legitimately verbose messages and resistance to
++ denial-of-service attacks.
+ """
+
+- maxCompressionPointers: int = MAX_COMPRESSION_POINTERS_PER_MESSAGE
++ maxCompressionPointers: int = 1000
+
+ def __init__(self, name: bytes | str = b""):
+ """
+@@ -2610,8 +2600,17 @@ class Message(tputil.FancyEqMixin):
+ header fields.
+ @ivar _sectionNames: The names of attributes representing the record
+ sections of this message.
++
++ @ivar maxCompressionPointers: Per-message cap on the total number of
++ compression-pointer dereferences L{decode} will follow across every
++ name in the message before raising L{DNSDecodeError}. Defaults to
++ C{1000}. Override it on a subclass or individual instance to tune
++ the trade-off between tolerance for legitimately verbose messages
++ and resistance to denial-of-service attacks.
+ """
+
++ maxCompressionPointers: int = 1000
++
+ compareAttributes = (
+ "id",
+ "answer",
+@@ -2830,7 +2829,7 @@ class Message(tputil.FancyEqMixin):
+ # performed across every name in this message. It is installed on
+ # the private context variable so nested record decoders pick it up
+ # without needing to thread it through each signature.
+- decodeContext = _DecodeContext(maxJumps=Name.maxCompressionPointers)
++ decodeContext = _DecodeContext(maxJumps=self.maxCompressionPointers)
+ with _installDecodeContext(decodeContext):
+ self.queries = []
+ for i in range(nqueries):
+diff --git a/src/twisted/names/test/test_dns.py b/src/twisted/names/test/test_dns.py
+index 9626115ab..3be6b4546 100644
+--- a/src/twisted/names/test/test_dns.py
++++ b/src/twisted/names/test/test_dns.py
+@@ -354,60 +354,51 @@ class NameTests(unittest.TestCase):
+
+ def test_rejectTooManyCompressionPointers(self):
+ """
+- L{Name.decode} raises L{dns.DNSDecodeError} when the number of
+- compression-pointer dereferences taken for a single message exceeds
+- the limit carried by the shared L{dns._DecodeContext} installed
+- through the private L{dns._decodeContextVar}.
+- """
+- # Five distinct pointers chained end-to-end, terminated by a zero
+- # label byte. With a maxJumps of three the fourth dereference must
+- # trip the safety limit.
++ L{Name.decode} raises L{dns.DNSDecodeError} when it would have to
++ follow more than L{Name.maxCompressionPointers} compression
++ pointers to finish decoding a name.
++ """
++ # Four distinct pointers chained end-to-end, terminated by a zero
++ # label byte. With maxCompressionPointers of three the fourth
++ # dereference must trip the safety limit.
+ payload = b"\xc0\x02\xc0\x04\xc0\x06\xc0\x08\x00"
+- context = dns._DecodeContext(maxJumps=3)
+- with dns._installDecodeContext(context):
+- self.assertRaises(
+- dns.DNSDecodeError,
+- dns.Name().decode,
+- BytesIO(payload),
+- )
++ name = dns.Name()
++ name.maxCompressionPointers = 3
++ self.assertRaises(
++ dns.DNSDecodeError, name.decode, BytesIO(payload)
++ )
+
+- def test_compressionPointerCounterIsShared(self):
++ def test_decodeRecoversAfterDNSDecodeError(self):
+ """
+- The L{dns._DecodeContext} counter accumulates across successive
+- L{Name.decode} calls, so that a message whose individual names are
+- each within bounds is still rejected when their aggregate exceeds
+- the configured limit. This mirrors production: L{Message.decode}
+- invokes L{Name.decode} many times against the same stream under one
+- shared context.
++ After L{Name.decode} raises L{dns.DNSDecodeError}, subsequent
++ L{Name.decode} calls continue to work. No residual
++ compression-pointer counter leaks across calls, so a legitimate
++ name decoded right after a hostile one still succeeds.
+ """
+- payload = b"\xc0\x02\xc0\x04\x00"
+- context = dns._DecodeContext(maxJumps=3)
+-
+- with dns._installDecodeContext(context):
+- stream = BytesIO(payload)
+- dns.Name().decode(stream)
+- self.assertEqual(context.jumps, 2)
+-
+- stream.seek(0)
+- self.assertRaises(
+- dns.DNSDecodeError,
+- dns.Name().decode,
+- stream,
+- )
++ # First, force a DNSDecodeError by decoding a payload that
++ # exceeds the configured limit.
++ hostile = dns.Name()
++ hostile.maxCompressionPointers = 3
++ self.assertRaises(
++ dns.DNSDecodeError,
++ hostile.decode,
++ BytesIO(b"\xc0\x02\xc0\x04\xc0\x06\xc0\x08\x00"),
++ )
+
+- def test_decodeWithoutContextIsBackwardsCompatible(self):
+- """
+- L{Name.decode} continues to work when called with no active
+- L{dns._decodeContextVar}, using a fresh per-call counter seeded
+- from L{dns.Name.maxCompressionPointers} so existing callers are
+- unaffected.
+- """
+- name = dns.Name()
++ # Then prove the process has not been poisoned: a legitimate
++ # name still decodes normally, both with a fresh instance and
++ # with the instance that just errored.
+ stream = BytesIO()
+ dns.Name(b"example.org").encode(stream)
++
++ fresh = dns.Name()
+ stream.seek(0)
+- name.decode(stream)
+- self.assertEqual(name.name, b"example.org")
++ fresh.decode(stream)
++ self.assertEqual(fresh.name, b"example.org")
++
++ stream.seek(0)
++ hostile.decode(stream)
++ self.assertEqual(hostile.name, b"example.org")
+
+ def test_equality(self):
+ """
+@@ -823,7 +814,7 @@ class MessageTests(unittest.SynchronousTestCase):
+ L{Message.decode} installs a shared compression-pointer counter and
+ raises L{dns.DNSDecodeError} when the aggregate number of pointer
+ dereferences across every record in the message exceeds
+- L{dns.MAX_COMPRESSION_POINTERS_PER_MESSAGE}.
++ L{dns.Message.maxCompressionPointers}.
+ """
+ chainLength = 100
+ numRecords = 8000
new file mode 100644
@@ -0,0 +1,23 @@
+From 2dc37caa8af3559e14fc1a1b36b049851d36943c Mon Sep 17 00:00:00 2001
+From: Adi Roiban <adiroiban@gmail.com>
+Date: Wed, 29 Apr 2026 15:55:05 +0100
+Subject: [PATCH] Update src/twisted/names/newsfragments/12626.bugfix
+
+CVE: CVE-2026-42304
+Upstream-Status: Backport [https://github.com/twisted/twisted/commit/9ca319ebf61386dd33354c4ade3946ef84ad58fb]
+
+(cherry picked from commit 9ca319ebf61386dd33354c4ade3946ef84ad58fb)
+Signed-off-by: Hetvi Thakar <hthakar@cisco.com>
+---
+ src/twisted/names/newsfragments/12626.bugfix | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/twisted/names/newsfragments/12626.bugfix b/src/twisted/names/newsfragments/12626.bugfix
+index 44896c3e5..179b92d83 100644
+--- a/src/twisted/names/newsfragments/12626.bugfix
++++ b/src/twisted/names/newsfragments/12626.bugfix
+@@ -1 +1 @@
+-twisted.names was fix for Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. CVE-REFERENCE HERE
+\ No newline at end of file
++twisted.names was fix for Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. CVE-2026-42304
+\ No newline at end of file
@@ -6,6 +6,14 @@ HOMEPAGE = "https://twisted.org"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://LICENSE;md5=5316a448a61a38d722c291f78d915d11"
+SRC_URI += "file://CVE-2026-42304_p1.patch \
+ file://CVE-2026-42304_p2.patch \
+ file://CVE-2026-42304_p3.patch \
+ file://CVE-2026-42304_p4.patch \
+ file://CVE-2026-42304_p5.patch \
+ file://CVE-2026-42304_p6.patch \
+ "
+
SRC_URI[sha256sum] = "1deb272358cb6be1e3e8fc6f9c8b36f78eb0fa7c2233d2dbe11ec6fee04ea316"
CVE_PRODUCT = "twisted"