Authlib: Setting `alg: none` and a blank signature appears to bypass signature verification (authlib authlib)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.54 % · percentile 45 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Modified
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.
Weaknesses (CWE)
- CWE-347 — Improper Verification of Cryptographic Signature
References
- https://github.com/authlib/authlib/security/advisories/GHSA-7wc2-qxgw-g8gg
- https://github.com/authlib/authlib/commit/a61c2acb807496e67f32051b5f1b1d5ccf8f0a75
- https://github.com/authlib/authlib/commit/b87c32ed07b8ae7f805873e1c9cafd1016761df7
- https://access.redhat.com/security/cve/CVE-2026-28802
- https://bugzilla.redhat.com/show_bug.cgi?id=2445120
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-28802.json
- https://access.redhat.com/errata/RHSA-2026:6309
- https://access.redhat.com/errata/RHSA-2026:5665
- https://access.redhat.com/errata/RHSA-2026:4942
- https://access.redhat.com/errata/RHSA-2026:6568
- https://access.redhat.com/errata/RHSA-2026:19375
- https://access.redhat.com/errata/RHSA-2026:5168
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | HIGH 7.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P | GitHub_M |
| CVSS 3.1 | CRITICAL 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | redhat-SADP |
| CVSS 4.0 | HIGH 7.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | CRITICAL 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | NVD · nvd@nist.gov (Primary) |
| CVSS 3.1 | CRITICAL 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | NVD · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Secondary) |
Advisories
- GHSA-7wc2-qxgw-g8gg — Authlib: Setting `alg: none` and a blank signature appears to bypass signature verification
- PYSEC-2026-2118 — 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 malici
European references
- ENISA EUVD · EUVD-2026-10009
- GCVE · GCVE-0-2026-28802
Affected configurations (NVD CPE)
cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:*≥ 1.6.5 < 1.6.7
Affected products
| Product | Versions |
|---|---|
| authlib · authlib | affected >= 1.6.5, < 1.6.7 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |