CVE-2026-27459
pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to `set_cookie_generate_callback` returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version 26.0.0, cookie values that are too long are now rejected.
Published:Mar 17, 2026
Last Modified:Aug 25, 2026
EPS:Mar 17, 2026
EPSS Score:0.00704
CVSS Score:9.8
Affected Products
Vendor
Product
Action
Vendor
Pyca
Product
Pyopenssl
Pyca
Pyopenssl
Vendor
Pyopenssl
Product
Pyopenssl
Pyopenssl
Pyopenssl
Exploits
No exploit reference
Common Weakness Enumeration
Common Attack Pattern Enumeration and Classification (CAPEC)
References
Common Vulnerability Scoring System
Attack Vector
Network
Adjacent
Local
Physical
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
