CVE-2026-28802: Authlib: Setting `alg: none` and a blank signature appears to bypass signature verification
(updated )
After upgrading the library from 1.5.2 to 1.6.0 (and the latest 1.6.5) it was noticed that previous tests involving passing a malicious JWT containing alg: none and an empty signature was passing the signature verification step without any changes to the application code when a failure was expected.
References
- github.com/advisories/GHSA-7wc2-qxgw-g8gg
- github.com/authlib/authlib
- github.com/authlib/authlib/commit/a61c2acb807496e67f32051b5f1b1d5ccf8f0a75
- github.com/authlib/authlib/commit/b87c32ed07b8ae7f805873e1c9cafd1016761df7
- github.com/authlib/authlib/security/advisories/GHSA-7wc2-qxgw-g8gg
- nvd.nist.gov/vuln/detail/CVE-2026-28802
Code Behaviors & Features
Detect and mitigate CVE-2026-28802 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 →