CVE-2026-0865: medium-severity vulnerability in Python Software Foundation CPython
wsgiref.headers.Headers allows header newline injection
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.9epss 0.6%
User-controlled header names and values containing newlines can allow injecting HTTP headers.
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:N/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/22e4d55285cee52bc4dbe061324e5f30bd4dee58https://github.com/python/cpython/commit/23e3c0ae867cca0130e441e776c9955b9027c510https://github.com/python/cpython/commit/286e3ac39984fe85a17f4ab39c64d382137aae5fhttps://github.com/python/cpython/commit/2f840249550e082dc351743f474ba56da10478d2https://github.com/python/cpython/commit/4802b96a2cde58570c24c13ef3289490980961c5https://github.com/python/cpython/commit/66da7bf6fe7b81e3ecc9c0a25bd47d4616c8d1a6https://github.com/python/cpython/commit/83ecd18779f286d872f68bfce175651e407d9fffhttps://github.com/python/cpython/commit/8bb044d29310bb05d15086cdaa8bf64867d61a97https://github.com/python/cpython/commit/bfba660085767f8c2d582134e9d511a85eda04cfhttps://github.com/python/cpython/commit/c592227ffb48679af9845a45dbb0875d975bb219https://github.com/python/cpython/commit/e4846a93ac07a8ae9aa18203af0dd13d6e7a6995https://github.com/python/cpython/commit/f7fceed79ca1bceae8dbe5ba5bc8928564da7211