Description
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.
Published: 2026-10-22
Score: 6.8 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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History

Fri, 23 Oct 2026 00:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Authlib: Default JWT bearer grant accepts assertions for the wrong audience
Weaknesses CWE-1188
CWE-287
References
Metrics cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-22T21:28:37.879Z

Reserved: 2026-10-21T20:34:25.600Z

Link: CVE-2026-114618

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-22T22:18:04.747

Modified: 2026-10-22T22:18:04.747

Link: CVE-2026-114618

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses
  • CWE-1188

    Initialization of a Resource with an Insecure Default

  • CWE-287

    Improper Authentication