CVE-2026-3644

HIGH

Incomplete control character validation in http.cookies

Title source: cna

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 (6)

Core 6

Core References

Vendor Advisory vendor-advisory

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

Patch patch

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

View Patch ZIP pw:eip

Issue Tracking issue-tracking

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

Patch patch

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

Patch patch

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

View Patch ZIP pw:eip

Patch patch

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

View Patch ZIP pw:eip

Scores

CVSS v3 7.5

EPSS 0.0039

EPSS Percentile 30.7%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-116 CWE-20

Status published

Products (6)

python/python 3.15.0 alpha1 (7 CPE variants)

python/python < 3.13.13

Python Software Foundation/CPython < 3.13.13

Python Software Foundation/CPython < 3.15.0

Python Software Foundation/CPython 3.14.0 - 3.14.4

Python Software Foundation/CPython 3.15.0a1 - 3.15.0a8

Published Mar 16, 2026

Tracked Since Mar 16, 2026