CVE-2025-13836: medium-severity vulnerability in Python Software Foundation CPython
Excessive read buffering DoS in http.client
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.3epss 1.7%
When reading an HTTP response from a server, if no read amount is specified, the default behavior will be to use Content-Length. This allows a malicious server to cause the client to read large amounts of data into memory, potentially causing OOM or other DoS.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA: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-2025-0938MEDIUMURL 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%CVE-2025-4517CRITICALArbitrary writes via tarfile realpath overflowEPSS 1.5%
References
https://github.com/python/cpython/commit/14b1fdb0a94b96f86fc7b86671ea9582b8676628https://github.com/python/cpython/commit/289f29b0fe38baf2d7cb5854f4bb573cc34a6a15https://github.com/python/cpython/commit/4ce27904b597c77d74dd93f2c912676021a99155https://github.com/python/cpython/commit/5a4c4a033a4a54481be6870aa1896fad732555b5https://github.com/python/cpython/commit/5dc101675fd22918facbbe0fecdc821502beaaf0https://github.com/python/cpython/commit/afc40bdd3dd71f343fd9016f6d8eebbacbd6587chttps://github.com/python/cpython/issues/119451https://github.com/python/cpython/pull/119454https://mail.python.org/archives/list/security-announce@python.org/thread/OQ6G7MKRQIS3OAREC3HNG3D2DPOU34XO/