CVE-2026-4224: Python

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

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.

Affected products

• Python Python: before 3.10.0 (fixed in 3.10.0); from 3.13.0, before 3.13.13 (fixed in 3.13.13); from 3.14.0, before 3.14.4 (fixed in 3.14.4); version 3.15.0 only

Published 2026-03-16. Last modified 2026-08-13.