Python has added a denylist for known compromised certificates to the "ssl" module to ensure user safety even without certificate revocation configured. Known compromised certificates will automatically be rejected regardless of the SSLContext policy configuration.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
Passive
Minimal interaction
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
Vulnerable Products
python software foundation:cpython
References 6
http://www.openwall.com/lists/oss-security/2026/10/20/29
NVD
https://github.com/python/cpython/pull/160042
NVD
https://github.com/python/cpython/issues/160040
NVD
https://emudhra.we-have-a-problem.com/
NVD
https://mail.python.org/archives/list/security-announce@python.org/thread/FNAJM…
NVD
http://www.openwall.com/lists/oss-security/2026/10/24/5
af854a3a-2127-422b-91ae-364da2661108