Vulnerability in Authlib
CVE-2026-28802
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (43.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 44th percentile — 43.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001
Affected products
- Authlib — versions >= 1.6.5, < 1.6.7
Weakness classification (CWE)
References
- github.com/authlib/authlib/security/advisories/GHSA-7wc2-qxgw-g8gg (Exploit, Vendor Advisory)
- github.com/authlib/authlib/commit/a61c2acb807496e67f32051b5f1b1d5ccf8f0a75 (Patch)
- github.com/authlib/authlib/commit/b87c32ed07b8ae7f805873e1c9cafd1016761df7 (Patch)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-28802?
- CVE-2026-28802 is a critical-severity vulnerability in Authlib, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.8/10. Published 2026-03-06.
- How severe is CVE-2026-28802?
- Critical severity. CVSS v3 base score is 9.8 out of 10.