diff mbox series

[scarthgap,09/12] python3-pyasn1: fix CVE-2026-30922

Message ID 20260409061639.1688205-10-jinfeng.wang.cn@windriver.com
State New
Headers show
Series Fix multiple CVEs | expand

Commit Message

Wang, Jinfeng (CN) April 9, 2026, 6:16 a.m. UTC
From: Jiaying Song <jiaying.song.cn@windriver.com>

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.3, the
`pyasn1` library is vulnerable to a Denial of Service (DoS) attack
caused by uncontrolled recursion when decoding ASN.1 data with deeply
nested structures. An attacker can supply a crafted payload containing
thousands of nested `SEQUENCE` (`0x30`) or `SET` (`0x31`) tags with
"Indefinite Length" (`0x80`) markers. This forces the decoder to
recursively call itself until the Python interpreter crashes with a
`RecursionError` or consumes all available memory (OOM), crashing the
host application. This is a distinct vulnerability from CVE-2026-23490
(which addressed integer overflows in OID decoding). The fix for
CVE-2026-23490 (`MAX_OID_ARC_CONTINUATION_OCTETS`) does not mitigate
this recursion issue. Version 0.6.3 fixes this specific issue.

References:
https://nvd.nist.gov/vuln/detail/CVE-2026-30922

Signed-off-by: Jiaying Song <jiaying.song.cn@windriver.com>
Signed-off-by: Jinfeng Wang <jinfeng.wang.cn@windriver.com>
---
 .../recipes-devtools/python/python-pyasn1.inc |   1 +
 .../python3-pyasn1/CVE-2026-30922.patch       | 257 ++++++++++++++++++
 2 files changed, 258 insertions(+)
 create mode 100644 meta/recipes-devtools/python/python3-pyasn1/CVE-2026-30922.patch
diff mbox series

Patch

diff --git a/meta/recipes-devtools/python/python-pyasn1.inc b/meta/recipes-devtools/python/python-pyasn1.inc
index 96b4a3b52a..d69cdf8877 100644
--- a/meta/recipes-devtools/python/python-pyasn1.inc
+++ b/meta/recipes-devtools/python/python-pyasn1.inc
@@ -19,6 +19,7 @@  inherit ptest
 SRC_URI += " \
        file://run-ptest \
        file://CVE-2026-23490.patch \
+       file://CVE-2026-30922.patch \
 "
 
 RDEPENDS:${PN}-ptest += " \
diff --git a/meta/recipes-devtools/python/python3-pyasn1/CVE-2026-30922.patch b/meta/recipes-devtools/python/python3-pyasn1/CVE-2026-30922.patch
new file mode 100644
index 0000000000..7eceaa2595
--- /dev/null
+++ b/meta/recipes-devtools/python/python3-pyasn1/CVE-2026-30922.patch
@@ -0,0 +1,257 @@ 
+From 85e901d1dacdcd17363cc2dd18a91cfb72363eeb Mon Sep 17 00:00:00 2001
+From: Simon Pichugin <simon.pichugin@gmail.com>
+Date: Thu, 19 Mar 2026 17:11:40 +0800
+Subject: [PATCH] Merge commit from fork
+
+CVE: CVE-2026-30922
+
+Upstream-Status: Backport [https://github.com/pyasn1/pyasn1/commit/25ad481c19]
+
+Signed-off-by: Jiaying Song <jiaying.song.cn@windriver.com>
+---
+ pyasn1/codec/ber/decoder.py     |  10 +++
+ tests/codec/ber/test_decoder.py | 114 ++++++++++++++++++++++++++++++++
+ tests/codec/cer/test_decoder.py |  22 ++++++
+ tests/codec/der/test_decoder.py |  40 +++++++++++
+ 4 files changed, 186 insertions(+)
+
+diff --git a/pyasn1/codec/ber/decoder.py b/pyasn1/codec/ber/decoder.py
+index be8ba65..da2a048 100644
+--- a/pyasn1/codec/ber/decoder.py
++++ b/pyasn1/codec/ber/decoder.py
+@@ -38,6 +38,7 @@ SubstrateUnderrunError = error.SubstrateUnderrunError
+ # Maximum number of continuation octets (high-bit set) allowed per OID arc.
+ # 20 octets allows up to 140-bit integers, supporting UUID-based OIDs
+ MAX_OID_ARC_CONTINUATION_OCTETS = 20
++MAX_NESTING_DEPTH = 100
+ 
+ 
+ class AbstractPayloadDecoder(object):
+@@ -1515,6 +1516,15 @@ class SingleItemDecoder(object):
+                  decodeFun=None, substrateFun=None,
+                  **options):
+ 
++        _nestingLevel = options.get('_nestingLevel', 0)
++
++        if _nestingLevel > MAX_NESTING_DEPTH:
++            raise error.PyAsn1Error(
++                'ASN.1 structure nesting depth exceeds limit (%d)' % MAX_NESTING_DEPTH
++            )
++
++        options['_nestingLevel'] = _nestingLevel + 1
++
+         allowEoo = options.pop('allowEoo', False)
+ 
+         if LOG:
+diff --git a/tests/codec/ber/test_decoder.py b/tests/codec/ber/test_decoder.py
+index f033dfd..226381a 100644
+--- a/tests/codec/ber/test_decoder.py
++++ b/tests/codec/ber/test_decoder.py
+@@ -1987,6 +1987,120 @@ class CompressedFilesTestCase(BaseTestCase):
+         finally:
+             os.remove(path)
+ 
++class NestingDepthLimitTestCase(BaseTestCase):
++    """Test protection against deeply nested ASN.1 structures (CVE prevention)."""
++
++    def testIndefLenSequenceNesting(self):
++        """Deeply nested indefinite-length SEQUENCEs must raise PyAsn1Error."""
++        # Each \x30\x80 opens a new indefinite-length SEQUENCE
++        payload = b'\x30\x80' * 200
++        try:
++            decoder.decode(payload)
++        except error.PyAsn1Error:
++            pass
++        else:
++            assert False, 'Deeply nested indef-length SEQUENCEs not rejected'
++
++    def testIndefLenSetNesting(self):
++        """Deeply nested indefinite-length SETs must raise PyAsn1Error."""
++        # Each \x31\x80 opens a new indefinite-length SET
++        payload = b'\x31\x80' * 200
++        try:
++            decoder.decode(payload)
++        except error.PyAsn1Error:
++            pass
++        else:
++            assert False, 'Deeply nested indef-length SETs not rejected'
++
++    def testDefiniteLenNesting(self):
++        """Deeply nested definite-length SEQUENCEs must raise PyAsn1Error."""
++        inner = b'\x05\x00'  # NULL
++        for _ in range(200):
++            length = len(inner)
++            if length < 128:
++                inner = b'\x30' + bytes([length]) + inner
++            else:
++                length_bytes = length.to_bytes(
++                    (length.bit_length() + 7) // 8, 'big')
++                inner = b'\x30' + bytes([0x80 | len(length_bytes)]) + \
++                    length_bytes + inner
++        try:
++            decoder.decode(inner)
++        except error.PyAsn1Error:
++            pass
++        else:
++            assert False, 'Deeply nested definite-length SEQUENCEs not rejected'
++
++    def testNestingUnderLimitWorks(self):
++        """Nesting within the limit must decode successfully."""
++        inner = b'\x05\x00'  # NULL
++        for _ in range(50):
++            length = len(inner)
++            if length < 128:
++                inner = b'\x30' + bytes([length]) + inner
++            else:
++                length_bytes = length.to_bytes(
++                    (length.bit_length() + 7) // 8, 'big')
++                inner = b'\x30' + bytes([0x80 | len(length_bytes)]) + \
++                    length_bytes + inner
++        asn1Object, _ = decoder.decode(inner)
++        assert asn1Object is not None, 'Valid nested structure rejected'
++
++    def testSiblingsDontIncreaseDepth(self):
++        """Sibling elements at the same level must not inflate depth count."""
++        # SEQUENCE containing 200 INTEGER siblings - should decode fine
++        components = b'\x02\x01\x01' * 200  # 200 x INTEGER(1)
++        length = len(components)
++        length_bytes = length.to_bytes(
++            (length.bit_length() + 7) // 8, 'big')
++        payload = b'\x30' + bytes([0x80 | len(length_bytes)]) + \
++            length_bytes + components
++        asn1Object, _ = decoder.decode(payload)
++        assert asn1Object is not None, 'Siblings incorrectly rejected'
++
++    def testErrorMessageContainsLimit(self):
++        """Error message must indicate the nesting depth limit."""
++        payload = b'\x30\x80' * 200
++        try:
++            decoder.decode(payload)
++        except error.PyAsn1Error as exc:
++            assert 'nesting depth' in str(exc).lower(), \
++                'Error message missing depth info: %s' % exc
++        else:
++            assert False, 'Expected PyAsn1Error'
++
++    def testNoRecursionError(self):
++        """Must raise PyAsn1Error, not RecursionError."""
++        payload = b'\x30\x80' * 50000
++        try:
++            decoder.decode(payload)
++        except error.PyAsn1Error:
++            pass
++        except RecursionError:
++            assert False, 'Got RecursionError instead of PyAsn1Error'
++
++    def testMixedNesting(self):
++        """Mixed SEQUENCE and SET nesting must be caught."""
++        # Alternate SEQUENCE (0x30) and SET (0x31) with indef length
++        payload = b''
++        for i in range(200):
++            payload += b'\x30\x80' if i % 2 == 0 else b'\x31\x80'
++        try:
++            decoder.decode(payload)
++        except error.PyAsn1Error:
++            pass
++        else:
++            assert False, 'Mixed nesting not rejected'
++
++    def testWithSchema(self):
++        """Deeply nested structures must be caught even with schema."""
++        payload = b'\x30\x80' * 200
++        try:
++            decoder.decode(payload, asn1Spec=univ.Sequence())
++        except error.PyAsn1Error:
++            pass
++        else:
++            assert False, 'Deeply nested with schema not rejected'
+ 
+ class NonStreamingCompatibilityTestCase(BaseTestCase):
+     def setUp(self):
+diff --git a/tests/codec/cer/test_decoder.py b/tests/codec/cer/test_decoder.py
+index 133affd..fbb1145 100644
+--- a/tests/codec/cer/test_decoder.py
++++ b/tests/codec/cer/test_decoder.py
+@@ -363,6 +363,28 @@ class SequenceDecoderWithExplicitlyTaggedSetOfOpenTypesTestCase(BaseTestCase):
+         assert s[0] == 3
+         assert s[1][0] == univ.OctetString(hexValue='02010C')
+ 
++class NestingDepthLimitTestCase(BaseTestCase):
++    """Test CER decoder protection against deeply nested structures."""
++
++    def testIndefLenNesting(self):
++        """Deeply nested indefinite-length SEQUENCEs must raise PyAsn1Error."""
++        payload = b'\x30\x80' * 200
++        try:
++            decoder.decode(payload)
++        except PyAsn1Error:
++            pass
++        else:
++            assert False, 'Deeply nested indef-length SEQUENCEs not rejected'
++
++    def testNoRecursionError(self):
++        """Must raise PyAsn1Error, not RecursionError."""
++        payload = b'\x30\x80' * 50000
++        try:
++            decoder.decode(payload)
++        except PyAsn1Error:
++            pass
++        except RecursionError:
++            assert False, 'Got RecursionError instead of PyAsn1Error'
+ 
+ suite = unittest.TestLoader().loadTestsFromModule(sys.modules[__name__])
+ 
+diff --git a/tests/codec/der/test_decoder.py b/tests/codec/der/test_decoder.py
+index 5bc9deb..b0fa867 100644
+--- a/tests/codec/der/test_decoder.py
++++ b/tests/codec/der/test_decoder.py
+@@ -361,6 +361,46 @@ class SequenceDecoderWithExplicitlyTaggedSetOfOpenTypesTestCase(BaseTestCase):
+         assert s[0] == 3
+         assert s[1][0] == univ.OctetString(hexValue='02010C')
+ 
++class NestingDepthLimitTestCase(BaseTestCase):
++    """Test DER decoder protection against deeply nested structures."""
++
++    def testDefiniteLenNesting(self):
++        """Deeply nested definite-length SEQUENCEs must raise PyAsn1Error."""
++        inner = b'\x05\x00'  # NULL
++        for _ in range(200):
++            length = len(inner)
++            if length < 128:
++                inner = b'\x30' + bytes([length]) + inner
++            else:
++                length_bytes = length.to_bytes(
++                    (length.bit_length() + 7) // 8, 'big')
++                inner = b'\x30' + bytes([0x80 | len(length_bytes)]) + \
++                    length_bytes + inner
++        try:
++            decoder.decode(inner)
++        except PyAsn1Error:
++            pass
++        else:
++            assert False, 'Deeply nested definite-length SEQUENCEs not rejected'
++
++    def testNoRecursionError(self):
++        """Must raise PyAsn1Error, not RecursionError."""
++        inner = b'\x05\x00'
++        for _ in range(200):
++            length = len(inner)
++            if length < 128:
++                inner = b'\x30' + bytes([length]) + inner
++            else:
++                length_bytes = length.to_bytes(
++                    (length.bit_length() + 7) // 8, 'big')
++                inner = b'\x30' + bytes([0x80 | len(length_bytes)]) + \
++                    length_bytes + inner
++        try:
++            decoder.decode(inner)
++        except PyAsn1Error:
++            pass
++        except RecursionError:
++            assert False, 'Got RecursionError instead of PyAsn1Error'
+ 
+ suite = unittest.TestLoader().loadTestsFromModule(sys.modules[__name__])
+ 
+-- 
+2.34.1
+