PYSEC-2026-4358
See a problem?- Import Source
- https://github.com/pypa/advisory-database/blob/main/vulns/authlib/PYSEC-2026-4358.yaml
- JSON Data
- https://api.osv.dev/v1/vulns/PYSEC-2026-4358
- Aliases
- Published
- 2026-10-22T22:18:04Z
- Modified
- 2026-10-30T10:00:02Z
- Severity
-
- 6.8 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:L/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 1.9.0, the default RFC 7523 JWTBearerGrant.get_audiences() returns an empty list, causing JWTBearerGrant.verify_claims() to require only that an aud claim exists without matching the current authorization server. An attacker holding a legitimate assertion for another service can present it to a server that shares the signing key and uses the default grant, obtaining an access token across a trust boundary. Implementations that override get_audiences() with the server's valid audience identifiers are not affected. This issue is fixed in version 1.9.0.
- 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 affectedFixed1.9.0
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