new file mode 100644
@@ -0,0 +1,249 @@
+From f61e8949f10a0e77ceba28a6639627e6e57bf167 Mon Sep 17 00:00:00 2001
+From: "J. Nick Koston" <nick@koston.org>
+Date: Sun, 7 Jun 2026 00:33:03 -0500
+Subject: [PATCH] [PR #12826/36df6c13 backport][3.14] Enforce max_line_size on
+ fragmented request target and reason in C parser (#12837)
+
+CVE: CVE-2026-54277
+Upstream-Status: Backport [https://github.com/aio-libs/aiohttp/commit/5ab61bb4cd88f19b712f12c7c9295fe262bf804d]
+
+Backport Changes:
+- Added aiohttp/_http_parser.c because Wrynose builds the
+ pre-generated C parser without running Cython.
+- Updated cb_on_url() and cb_on_status() to enforce max_line_size
+ against the accumulated parser buffer.
+
+(cherry picked from commit 5ab61bb4cd88f19b712f12c7c9295fe262bf804d)
+Signed-off-by: Darsh Kelaiya <dkelaiya@cisco.com>
+---
+ CHANGES/12826.bugfix.rst | 1 +
+ aiohttp/_http_parser.c | 36 ++++++++++++++++++------------------
+ aiohttp/_http_parser.pyx | 4 ++--
+ tests/test_http_parser.py | 22 ++++++++++++++++++++++
+ 4 files changed, 43 insertions(+), 20 deletions(-)
+ create mode 100644 CHANGES/12826.bugfix.rst
+
+diff --git a/CHANGES/12826.bugfix.rst b/CHANGES/12826.bugfix.rst
+new file mode 100644
+index 000000000..7e095615d
+--- /dev/null
++++ b/CHANGES/12826.bugfix.rst
+@@ -0,0 +1 @@
++Fixed the C HTTP parser not enforcing ``max_line_size`` on a request target or response reason phrase that is split across multiple reads; each fragment was checked on its own, so an accumulated line could exceed the limit without raising ``LineTooLong``. The accumulated length is now checked, matching the pure-Python parser -- by :user:`bdraco`.
+diff --git a/aiohttp/_http_parser.c b/aiohttp/_http_parser.c
+index 911c9aa65..14c5b3350 100644
+--- a/aiohttp/_http_parser.c
++++ b/aiohttp/_http_parser.c
+@@ -14760,7 +14760,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_url(llhttp_t *__pyx_v_parser, c
+ * const char *at, size_t length) except -1:
+ * cdef HttpParser pyparser = <HttpParser>parser.data # <<<<<<<<<<<<<<
+ * try:
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ */
+ __pyx_t_1 = ((PyObject *)__pyx_v_parser->data);
+ __Pyx_INCREF(__pyx_t_1);
+@@ -14771,7 +14771,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_url(llhttp_t *__pyx_v_parser, c
+ * const char *at, size_t length) except -1:
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try: # <<<<<<<<<<<<<<
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * status = pyparser._buf + at[:length]
+ */
+ {
+@@ -14786,16 +14786,16 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_url(llhttp_t *__pyx_v_parser, c
+ /* "aiohttp/_http_parser.pyx":721
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try:
+- * if length > pyparser._max_line_size: # <<<<<<<<<<<<<<
++ * if len(pyparser._buf) + length > pyparser._max_line_size: # <<<<<<<<<<<<<<
+ * status = pyparser._buf + at[:length]
+ * raise LineTooLong(status[:100] + b"...", pyparser._max_line_size)
+ */
+- __pyx_t_5 = (__pyx_v_length > __pyx_v_pyparser->_max_line_size);
++ __pyx_t_5 = ((__Pyx_PyByteArray_GET_SIZE(__pyx_v_pyparser->_buf) + __pyx_v_length) > __pyx_v_pyparser->_max_line_size);
+ if (unlikely(__pyx_t_5)) {
+
+ /* "aiohttp/_http_parser.pyx":722
+ * try:
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * status = pyparser._buf + at[:length] # <<<<<<<<<<<<<<
+ * raise LineTooLong(status[:100] + b"...", pyparser._max_line_size)
+ * extend(pyparser._buf, at, length)
+@@ -14809,7 +14809,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_url(llhttp_t *__pyx_v_parser, c
+ __pyx_t_6 = 0;
+
+ /* "aiohttp/_http_parser.pyx":723
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * status = pyparser._buf + at[:length]
+ * raise LineTooLong(status[:100] + b"...", pyparser._max_line_size) # <<<<<<<<<<<<<<
+ * extend(pyparser._buf, at, length)
+@@ -14854,7 +14854,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_url(llhttp_t *__pyx_v_parser, c
+ /* "aiohttp/_http_parser.pyx":721
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try:
+- * if length > pyparser._max_line_size: # <<<<<<<<<<<<<<
++ * if len(pyparser._buf) + length > pyparser._max_line_size: # <<<<<<<<<<<<<<
+ * status = pyparser._buf + at[:length]
+ * raise LineTooLong(status[:100] + b"...", pyparser._max_line_size)
+ */
+@@ -14878,7 +14878,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_url(llhttp_t *__pyx_v_parser, c
+ * const char *at, size_t length) except -1:
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try: # <<<<<<<<<<<<<<
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * status = pyparser._buf + at[:length]
+ */
+ }
+@@ -14968,7 +14968,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_url(llhttp_t *__pyx_v_parser, c
+ * const char *at, size_t length) except -1:
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try: # <<<<<<<<<<<<<<
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * status = pyparser._buf + at[:length]
+ */
+ __pyx_L5_except_error:;
+@@ -15045,7 +15045,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_status(llhttp_t *__pyx_v_parser
+ * const char *at, size_t length) except -1:
+ * cdef HttpParser pyparser = <HttpParser>parser.data # <<<<<<<<<<<<<<
+ * try:
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ */
+ __pyx_t_1 = ((PyObject *)__pyx_v_parser->data);
+ __Pyx_INCREF(__pyx_t_1);
+@@ -15056,7 +15056,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_status(llhttp_t *__pyx_v_parser
+ * const char *at, size_t length) except -1:
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try: # <<<<<<<<<<<<<<
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * reason = pyparser._buf + at[:length]
+ */
+ {
+@@ -15071,16 +15071,16 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_status(llhttp_t *__pyx_v_parser
+ /* "aiohttp/_http_parser.pyx":736
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try:
+- * if length > pyparser._max_line_size: # <<<<<<<<<<<<<<
++ * if len(pyparser._buf) + length > pyparser._max_line_size: # <<<<<<<<<<<<<<
+ * reason = pyparser._buf + at[:length]
+ * raise LineTooLong(reason[:100] + b"...", pyparser._max_line_size)
+ */
+- __pyx_t_5 = (__pyx_v_length > __pyx_v_pyparser->_max_line_size);
++ __pyx_t_5 = ((__Pyx_PyByteArray_GET_SIZE(__pyx_v_pyparser->_buf) + __pyx_v_length) > __pyx_v_pyparser->_max_line_size);
+ if (unlikely(__pyx_t_5)) {
+
+ /* "aiohttp/_http_parser.pyx":737
+ * try:
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * reason = pyparser._buf + at[:length] # <<<<<<<<<<<<<<
+ * raise LineTooLong(reason[:100] + b"...", pyparser._max_line_size)
+ * extend(pyparser._buf, at, length)
+@@ -15094,7 +15094,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_status(llhttp_t *__pyx_v_parser
+ __pyx_t_6 = 0;
+
+ /* "aiohttp/_http_parser.pyx":738
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * reason = pyparser._buf + at[:length]
+ * raise LineTooLong(reason[:100] + b"...", pyparser._max_line_size) # <<<<<<<<<<<<<<
+ * extend(pyparser._buf, at, length)
+@@ -15139,7 +15139,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_status(llhttp_t *__pyx_v_parser
+ /* "aiohttp/_http_parser.pyx":736
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try:
+- * if length > pyparser._max_line_size: # <<<<<<<<<<<<<<
++ * if len(pyparser._buf) + length > pyparser._max_line_size: # <<<<<<<<<<<<<<
+ * reason = pyparser._buf + at[:length]
+ * raise LineTooLong(reason[:100] + b"...", pyparser._max_line_size)
+ */
+@@ -15163,7 +15163,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_status(llhttp_t *__pyx_v_parser
+ * const char *at, size_t length) except -1:
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try: # <<<<<<<<<<<<<<
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * reason = pyparser._buf + at[:length]
+ */
+ }
+@@ -15253,7 +15253,7 @@ static int __pyx_f_7aiohttp_12_http_parser_cb_on_status(llhttp_t *__pyx_v_parser
+ * const char *at, size_t length) except -1:
+ * cdef HttpParser pyparser = <HttpParser>parser.data
+ * try: # <<<<<<<<<<<<<<
+- * if length > pyparser._max_line_size:
++ * if len(pyparser._buf) + length > pyparser._max_line_size:
+ * reason = pyparser._buf + at[:length]
+ */
+ __pyx_L5_except_error:;
+diff --git a/aiohttp/_http_parser.pyx b/aiohttp/_http_parser.pyx
+index 5da835bc6..e1edee310 100644
+--- a/aiohttp/_http_parser.pyx
++++ b/aiohttp/_http_parser.pyx
+@@ -718,7 +718,7 @@ cdef int cb_on_url(cparser.llhttp_t* parser,
+ const char *at, size_t length) except -1:
+ cdef HttpParser pyparser = <HttpParser>parser.data
+ try:
+- if length > pyparser._max_line_size:
++ if len(pyparser._buf) + length > pyparser._max_line_size:
+ status = pyparser._buf + at[:length]
+ raise LineTooLong(status[:100] + b"...", pyparser._max_line_size)
+ extend(pyparser._buf, at, length)
+@@ -733,7 +733,7 @@ cdef int cb_on_status(cparser.llhttp_t* parser,
+ const char *at, size_t length) except -1:
+ cdef HttpParser pyparser = <HttpParser>parser.data
+ try:
+- if length > pyparser._max_line_size:
++ if len(pyparser._buf) + length > pyparser._max_line_size:
+ reason = pyparser._buf + at[:length]
+ raise LineTooLong(reason[:100] + b"...", pyparser._max_line_size)
+ extend(pyparser._buf, at, length)
+diff --git a/tests/test_http_parser.py b/tests/test_http_parser.py
+index 25604dbcc..8cb591f20 100644
+--- a/tests/test_http_parser.py
++++ b/tests/test_http_parser.py
+@@ -1272,6 +1272,17 @@ def test_http_request_max_status_line_under_limit(parser: HttpRequestParser) ->
+ assert msg.url == URL("/path" + path.decode())
+
+
++def test_http_request_max_status_line_fragmented(
++ parser: HttpRequestParser,
++) -> None:
++ # Split an overlong request target across reads so that each callback
++ # fragment is under the limit but the accumulated target is not.
++ match = "400, message:\n Got more than 8190 bytes when reading"
++ with pytest.raises(http_exceptions.LineTooLong, match=match):
++ parser.feed_data(b"GET /" + b"a" * 8000)
++ parser.feed_data(b"a" * 8000 + b" HTTP/1.1\r\nHost: a\r\n\r\n")
++
++
+ def test_http_response_parser_utf8(response) -> None:
+ text = "HTTP/1.1 200 Ok\r\nx-test:ัะตัั\r\n\r\n".encode()
+
+@@ -1349,6 +1360,17 @@ def test_http_response_parser_status_line_under_limit(
+ assert msg.reason == reason.decode()
+
+
++def test_http_response_parser_status_line_too_long_fragmented(
++ response: HttpResponseParser,
++) -> None:
++ # Split an overlong reason phrase across reads so that each callback
++ # fragment is under the limit but the accumulated reason is not.
++ match = "400, message:\n Got more than 8190 bytes when reading"
++ with pytest.raises(http_exceptions.LineTooLong, match=match):
++ response.feed_data(b"HTTP/1.1 200 " + b"a" * 8000)
++ response.feed_data(b"a" * 8000 + b"\r\n\r\n")
++
++
+ def test_http_response_parser_bad_version(response) -> None:
+ with pytest.raises(http_exceptions.BadHttpMessage):
+ response.feed_data(b"HT/11 200 Ok\r\n\r\n")
+--
+2.35.6
+
@@ -13,6 +13,7 @@ SRC_URI += " \
file://CVE-2026-54274.patch \
file://CVE-2026-54275.patch \
file://CVE-2026-54276.patch \
+ file://CVE-2026-54277.patch \
"
CVE_PRODUCT = "aiohttp"