CVE-2025-6069: medium-severity vulnerability in Python Software Foundation CPython
HTMLParser quadratic complexity when processing malformed inputs
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 4.3epss 0.6%
The html.parser.HTMLParser class had worse-case quadratic complexity when processing certain crafted malformed inputs potentially leading to amplified denial-of-service.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
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/4455cbabf991e202185a25a631af206f60bbc949https://github.com/python/cpython/commit/6eb6c5dbfb528bd07d77b60fd71fd05d81d45c41https://github.com/python/cpython/commit/8d1b3dfa09135affbbf27fb8babcf3c11415df49https://github.com/python/cpython/commit/ab0893fd5c579d9cea30841680e6d35fc478afb5https://github.com/python/cpython/commit/d851f8e258c7328814943e923a7df81bca15df4bhttps://github.com/python/cpython/commit/f3c6f882cddc8dc30320d2e73edf019e201394fchttps://github.com/python/cpython/commit/fdc9d214c01cb4588f540cfa03726bbf2a33fc15https://github.com/python/cpython/issues/135462https://github.com/python/cpython/pull/135464https://mail.python.org/archives/list/security-announce@python.org/thread/K5PIYLR6EP3WR7ZOKKYQUWEDNQVUXOYM/