PT-2026-25791 · Python · Cpython

Bénédikt Tran + 2 · Published 2026-03-16 · Updated 2026-03-16 · CVE-2026-4224

Mitre

CVSS v4.0

6.0

6.0

Medium

Base vector

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

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.

Fix

Uncontrolled Recursion

Weakness Enumeration

CWE-674

Related Identifiers

CVE-2026-4224

Affected Products

Cpython

References · 7

• https://github.com/python/cpython/pull/145987 · Patch
• https://github.com/python/cpython/commit/e0a8a6da90597a924b300debe045cdb4628ee1f3 · Patch
• https://github.com/python/cpython/commit/eb0e8be3a7e11b87d198a2c3af1ed0eccf532768 · Patch
• https://github.com/python/cpython/commit/196edfb06a7458377d4d0f4b3cd41724c1f3bd4a · Patch
• https://mail.python.org/archives/list/[e-mail]/thread/5M7CGUW3XBRY7II4DK43KF7NQQ3TPZ6R · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-4224 · Security Note
• https://github.com/python/cpython/issues/145986 · Note