CVE-2026-27459

Name of the Vulnerable Software and Affected Versions pyOpenSSL versions 22.0.0 through 25.3.0

Description pyOpenSSL is a Python wrapper around the OpenSSL library. If a user-provided callback to the set cookie generate callback function returned a cookie value exceeding 256 bytes, pyOpenSSL would cause a buffer overflow in an OpenSSL-provided buffer. Starting with version 26.0.0, pyOpenSSL rejects cookie values that are too long, mitigating the issue. The set cookie generate callback function is used to generate cookies for use with DTLS (Datagram Transport Layer Security).

Recommendations pyOpenSSL versions 22.0.0 through 25.3.0 should be updated to version 26.0.0 or later.