High severityNVD Advisory· Published Mar 6, 2026· Updated Mar 6, 2026
Authlib: Setting `alg: none` and a blank signature appears to bypass signature verification
CVE-2026-28802
Description
Authlib is a Python library which builds OAuth and OpenID Connect servers. From version 1.6.5 to before version 1.6.7, 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.. This issue has been patched in version 1.6.7.
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LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
authlibPyPI | >= 1.6.5, < 1.6.7 | 1.6.7 |
Affected products
4- osv-coords3 versions
< 3.1.8-r0+ 2 more
- (no CPE)range: < 3.1.8-r0
- (no CPE)range: < 3.1.8-r0
- (no CPE)range: >= 1.6.5, < 1.6.7
Patches
Vulnerability mechanics
References
5- github.com/advisories/GHSA-7wc2-qxgw-g8ggghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-28802ghsaADVISORY
- github.com/authlib/authlib/commit/a61c2acb807496e67f32051b5f1b1d5ccf8f0a75ghsax_refsource_MISCWEB
- github.com/authlib/authlib/commit/b87c32ed07b8ae7f805873e1c9cafd1016761df7ghsax_refsource_MISCWEB
- github.com/authlib/authlib/security/advisories/GHSA-7wc2-qxgw-g8ggghsax_refsource_CONFIRMWEB
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