CVE-2026-4224

MEDIUM

Stack overflow parsing XML with deeply nested DTD content models

Title source: cna

Description

When an Expat parser with a registered ElementDeclHandler parses an inline document type definition containing a deeply nested content model a C stack overflow occurs.

References (9)

[Mailing List] http://www.openwall.com/lists/oss-security/2026/03/16/4

[Patch] https://github.com/python/cpython/commit/eb0e8be3a7e11b87d198a2c3af1ed0eccf532768

[Vendor Advisory] https://mail.python.org/archives/list/[email protected]/thread/5M7CGUW3XBRY7II4DK43KF7NQQ3TPZ6R/

[Issue Tracking] https://github.com/python/cpython/issues/145986

[Patch] https://github.com/python/cpython/pull/145987

[Patch] https://github.com/python/cpython/commit/196edfb06a7458377d4d0f4b3cd41724c1f3bd4a

[Patch] https://github.com/python/cpython/commit/e0a8a6da90597a924b300debe045cdb4628ee1f3

View Patch ZIP pw:eip

[Patch] https://github.com/python/cpython/commit/642865ddf4b232da1f3b1f7abcfa3254c4bfe785

[Patch] https://github.com/python/cpython/commit/af856a7177326ac25d9f66cc6dd28b554d914fee

Scores

CVSS v4 6.0

EPSS 0.0003

EPSS Percentile 10.1%

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-674

Status published

Products (4)

Python Software Foundation/CPython < 3.13.13

Python Software Foundation/CPython < 3.15.0

Python Software Foundation/CPython 3.14.0 - 3.14.4

Python Software Foundation/CPython 3.15.0a1 - 3.15.0a8

Published Mar 16, 2026

Tracked Since Mar 17, 2026