CVE-2026-4224: medium-severity vulnerability in Python Software Foundation CPython
Stack overflow parsing XML with deeply nested DTD content models
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6epss 0.7%
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.
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
Affected products
Python Software Foundation · CPythonRelated CVEs — Python Software Foundation CPython
In the same product, most dangerous first.
CVE-2024-7592HIGHQuadratic complexity parsing cookies with backslashesEPSS 2.3%CVE-2024-6232HIGHRegular-expression DoS when parsing TarFile headersEPSS 2.2%CVE-2024-12254HIGHUnbounded memory buffering in SelectorSocketTransport.writelines()EPSS 1.9%CVE-2025-13836MEDIUMExcessive read buffering DoS in http.clientEPSS 1.7%CVE-2025-0938MEDIUMURL parser allowed square brackets in domain namesEPSS 1.6%CVE-2025-4138HIGHBypassing extraction filter to create symlinks to arbitrary targets outside extraction directoryEPSS 1.5%
References
https://github.com/python/cpython/commit/196edfb06a7458377d4d0f4b3cd41724c1f3bd4ahttps://github.com/python/cpython/commit/24ce88b285f56ee11626cf5e472af3cd8cc7c621https://github.com/python/cpython/commit/642865ddf4b232da1f3b1f7abcfa3254c4bfe785https://github.com/python/cpython/commit/af856a7177326ac25d9f66cc6dd28b554d914feehttps://github.com/python/cpython/commit/e0a8a6da90597a924b300debe045cdb4628ee1f3https://github.com/python/cpython/commit/eb0e8be3a7e11b87d198a2c3af1ed0eccf532768https://github.com/python/cpython/issues/145986https://github.com/python/cpython/pull/145987https://mail.python.org/archives/list/security-announce@python.org/thread/5M7CGUW3XBRY7II4DK43KF7NQQ3TPZ6R/http://www.openwall.com/lists/oss-security/2026/03/16/4