PYSEC-2026-4356
See a problem?- Import Source
- https://github.com/pypa/advisory-database/blob/main/vulns/authlib/PYSEC-2026-4356.yaml
- JSON Data
- https://api.osv.dev/v1/vulns/PYSEC-2026-4356
- Aliases
- Published
- 2026-10-22T22:18:04Z
- Modified
- 2026-10-30T10:00:02Z
- Severity
-
- 9.1 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N CVSS Calculator
- Summary
- [none]
- Details
-
Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.1, Authlib's OctKey.import_key() and HMAC signing and verification path accept zero-length key material. If an application's secret lookup can return an empty string or empty bytes, a remote attacker can compute the deterministic HS256, HS384, or HS512 signature for arbitrary token claims and have Authlib treat the token as authentic. This issue is fixed in version 1.9.1.
- References
Affected packages
PyPI / authlib
Package
- Name
- authlib
- View open source insights on deps.dev
- Purl
- pkg:pypi/authlib
Affected ranges
- Type
- ECOSYSTEM
- Events
-
Introduced0 Unknown introduced version / All previous versions are affectedFixed1.9.1
Affected versions
0.*
0.1rc0
0.1
0.2
0.2.1
0.3
0.4
0.4.1
0.5
0.5.1
0.6
0.7
0.8
0.9
0.10
0.11
0.12
0.12.1
0.13
0.14
0.14.1
0.14.2
0.14.3
0.15
0.15.1
0.15.2
0.15.3
0.15.4
0.15.5
0.15.6
1.*
1.0.0a1
1.0.0a2
1.0.0b1
1.0.0b2
1.0.0rc1
1.0.0
1.0.1
1.1.0
1.2.0
1.2.1
1.3.0
1.3.1
1.3.2
1.4.0
1.4.1
1.5.0
1.5.1
1.5.2
1.6.0
1.6.1
1.6.2
1.6.3
1.6.4
1.6.5
1.6.6
1.6.7
1.6.8
1.6.9
1.6.10
1.6.11
1.6.12
1.7.0
1.7.1
1.7.2
1.8.0
1.9.0