Vulnerability Report

CVE-2026-3644

Title: Incomplete fix for control characters in http.cookies.Morsel

Input Validation Error

Proof Of Concept

No public PoC currently indexed for CVE-2026-3644.

CWE Category NVD-CWE-noinfo

Published Date Mar 16, 2026

Modified Date Jun 30, 2026

Exploit Status Not Found

Score 6.0 CVSS v4.0

Exploit Probability (EPSS)

0.42%

Vulnerability Summary

CVE-2026-3644: 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().

Impacted Vendors

python 1

python_software_foundation 1

Reference Links

https://github.com/python/cpython/commit/57e88c1cf95e1481b94ae57abe1010469d47a6b4 https://github.com/python/cpython/commit/62ceb396fcbe69da1ded3702de586f4072b590dd https://github.com/python/cpython/commit/d16ecc6c3626f0e2cc8f08c309c83934e8a979dd https://github.com/python/cpython/issues/145599 https://github.com/python/cpython/pull/145600 https://mail.python.org/archives/list/[email protected]/thread/H6CADMBCDRFGWCMOXWUIHFJNV43GABJ7/

CVSS v4.0

Source Entity [email protected]

Severity MEDIUM

6.0

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

N/A

RAW 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1

Source Entity [email protected]

Severity HIGH

7.5