CVE-2026-4224: Vulnerability in Python Software Foundation CPython
CVE-2026-4224 is a medium severity vulnerability in the Python Software Foundation's CPython implementation. It arises when the Expat XML parser, configured with a registered ElementDeclHandler, processes an inline DTD containing a deeply nested content model, causing a C stack overflow. This affects CPython versions from 0 up to 3.15.0a1. No known exploits have been reported in the wild. Currently, there is no patch or official fix available for this vulnerability.
AI Analysis
Technical Summary
This vulnerability in CPython involves the Expat XML parser's handling of inline DTDs with deeply nested content models when an ElementDeclHandler is registered. The deeply nested structure leads to a C stack overflow, potentially causing a denial of service or crash. It affects CPython versions 0 through 3.15.0a1. The CVSS 4.0 base score is 6.0, indicating medium severity. No exploits are known, and no remediation or patch has been published by the Python Software Foundation as of the publication date.
Potential Impact
The vulnerability can cause a C stack overflow in the Expat XML parser within CPython, potentially leading to application crashes or denial of service. There is no evidence of exploitation in the wild. The impact is limited to affected CPython versions when processing maliciously crafted XML with deeply nested DTD content models and a registered ElementDeclHandler.
Mitigation Recommendations
Patch status is not yet confirmed — check the Python Software Foundation advisory for current remediation guidance. Until a patch or official fix is released, users should consider avoiding processing untrusted XML documents with deeply nested DTDs using CPython versions up to 3.15.0a1. Monitor official Python channels for updates.
CVE-2026-4224: Vulnerability in Python Software Foundation CPython
Description
CVE-2026-4224 is a medium severity vulnerability in the Python Software Foundation's CPython implementation. It arises when the Expat XML parser, configured with a registered ElementDeclHandler, processes an inline DTD containing a deeply nested content model, causing a C stack overflow. This affects CPython versions from 0 up to 3.15.0a1. No known exploits have been reported in the wild. Currently, there is no patch or official fix available for this vulnerability.
CVSS v4.0
Score 6.0medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability in CPython involves the Expat XML parser's handling of inline DTDs with deeply nested content models when an ElementDeclHandler is registered. The deeply nested structure leads to a C stack overflow, potentially causing a denial of service or crash. It affects CPython versions 0 through 3.15.0a1. The CVSS 4.0 base score is 6.0, indicating medium severity. No exploits are known, and no remediation or patch has been published by the Python Software Foundation as of the publication date.
Potential Impact
The vulnerability can cause a C stack overflow in the Expat XML parser within CPython, potentially leading to application crashes or denial of service. There is no evidence of exploitation in the wild. The impact is limited to affected CPython versions when processing maliciously crafted XML with deeply nested DTD content models and a registered ElementDeclHandler.
Mitigation Recommendations
Patch status is not yet confirmed — check the Python Software Foundation advisory for current remediation guidance. Until a patch or official fix is released, users should consider avoiding processing untrusted XML documents with deeply nested DTDs using CPython versions up to 3.15.0a1. Monitor official Python channels for updates.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- PSF
- Date Reserved
- 2026-03-15T18:10:54.886Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 69b84a02771bdb174918693d
Added to database: 3/16/2026, 6:20:50 PM
Last enriched: 6/3/2026, 9:16:06 PM
Last updated: 6/15/2026, 10:21:49 AM
Views: 204
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