CVE-2026-3644

medium

Description

The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_output() lacked the output validation applied to BaseCookie.output().

References

https://mail.python.org/archives/list/[email protected]/thread/H6CADMBCDRFGWCMOXWUIHFJNV43GABJ7/

https://github.com/python/cpython/pull/145600

https://github.com/python/cpython/issues/145599

https://github.com/python/cpython/commit/d16ecc6c3626f0e2cc8f08c309c83934e8a979dd

https://github.com/python/cpython/commit/62ceb396fcbe69da1ded3702de586f4072b590dd

https://github.com/python/cpython/commit/57e88c1cf95e1481b94ae57abe1010469d47a6b4

Details

Source: Mitre, NVD

Published: 2026-03-16

Updated: 2026-03-17

Risk Information

CVSS v2

Base Score: 5

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N

Severity: Medium

CVSS v3

Base Score: 7.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Severity: High

CVSS v4

Base Score: 6

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N

Severity: Medium

EPSS

EPSS: 0.00101