CR/LF bytes were not rejected by HTTP client proxy tunnel headers or host.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
High
Admin privileges needed
User Interaction
Passive
Minimal interaction
Impact Assessment
Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v4.0
References 5
https://github.com/python/cpython/commit/05ed7ce7ae9e17c23a04085b2539fe6d6d3cef…
cna@python.org
https://github.com/python/cpython/issues/146211
cna@python.org
https://github.com/python/cpython/pull/146212
cna@python.org
https://mail.python.org/archives/list/security-announce@python.org/thread/2IVPA…
cna@python.org
http://www.openwall.com/lists/oss-security/2026/04/11/4
af854a3a-2127-422b-91ae-364da2661108