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().
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 6
https://github.com/python/cpython/commit/57e88c1cf95e1481b94ae57abe1010469d47a6…
cna@python.org
https://github.com/python/cpython/commit/62ceb396fcbe69da1ded3702de586f4072b590…
cna@python.org
https://github.com/python/cpython/commit/d16ecc6c3626f0e2cc8f08c309c83934e8a979…
cna@python.org
https://github.com/python/cpython/issues/145599
cna@python.org
https://github.com/python/cpython/pull/145600
cna@python.org
https://mail.python.org/archives/list/security-announce@python.org/thread/H6CAD…
cna@python.org