CVE-2026-27459: pyOpenSSL DTLS cookie callback buffer overflow
(updated )
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.
Cookie values that are too long are now rejected.
References
- github.com/advisories/GHSA-5pwr-322w-8jr4
- github.com/pyca/pyopenssl
- github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst
- github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408
- github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4
- nvd.nist.gov/vuln/detail/CVE-2026-27459
Code Behaviors & Features
Detect and mitigate CVE-2026-27459 with GitLab Dependency Scanning
Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →