CVE-2026-37979: Keycloak: keycloak: information disclosure via oidc token introspection endpoint audience bypass

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-19 · updated 2026-10-29
Weakness: CWE-639

Description

A flaw was found in Keycloak. This access control vulnerability in Keycloak's OpenID Connect (OIDC) token introspection endpoint allows a confidential client to bypass audience restrictions. An attacker-controlled client with valid credentials can retrieve sensitive token claims intended for other resource servers, compromising the confidentiality of lightweight access tokens. This issue can be exploited remotely by any confidential client in the realm with valid credentials.

Affected products

Red Hat build of Keycloak 26.4: from 26.4 before 26.4.12 — fixed in 26.4.12
Red Hat build of Keycloak 26.4: all versions — fixed in 26.4.12-1

How to fix

Upgrade to a fixed version: Red Hat build of Keycloak 26.4 26.4.12; Red Hat build of Keycloak 26.4 26.4.12-1. Check the vendor advisory for mitigations.

References

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