What’s Vulnerable › Vulnerabilities

CVE-2026-18208: Keycloak-services: keycloak-services: inactive out-of-audience token introspection leaks signed jwt claim

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-31 · updated 2026-08-07
• Weakness: CWE-862

Description

A flaw was found in the OIDC token introspection endpoint of the keycloak-services component. Keycloak is an open-source identity and access management solution used to secure modern applications and services. The issue occurs when a confidential client, configured to receive signed JWT introspection responses, attempts to introspect a token issued for a different audience. Although the endpoint correctly identifies the token as inactive for that client, it still returns the full set of token claims within a signed JWT field. This allows an unauthorized client to bypass audience-based restrictions and access sensitive information contained in the token.

Affected products

• Red Hat build of Keycloak 26.4: all versions

References

• https://access.redhat.com/security/cve/CVE-2026-18208
• https://bugzilla.redhat.com/show_bug.cgi?id=2508304

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