Vulnerability in Python
CVE-2026-4224
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.
EPSS: 0.001 (15.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Python — versions 3.15.0
- Python Software Foundation Cpython — versions 0, 3.14.0, 3.15.0a1
Weakness classification (CWE)
References
- cna@python.org (Patch, patch)
- cna@python.org (vendor-advisory, Third Party Advisory)
- cna@python.org (issue-tracking, Issue Tracking)
- cna@python.org (Patch, patch)
- cna@python.org (Patch, patch)
- cna@python.org (Patch, patch)
- cna@python.org (Patch, patch)
- cna@python.org (Patch, patch)
- af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-4224?
- CVE-2026-4224 is a high-severity vulnerability in Python, classified under Uncontrolled Recursion. CVSS score: 7.5/10. Published 2026-03-16.
- How severe is CVE-2026-4224?
- High severity. CVSS v3 base score is 7.5 out of 10.