CVE-2026-18208 — MEDIUM (6.5)

Vulnerability 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.

CVSS Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

NONE

Availability

NONE

Affected Products

Vendor	Product	Versions
Redhat	Build Of Keycloak	-

Related Weaknesses (CWE)

CWE-862

References

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

FAQ

What is CVE-2026-18208?

CVE-2026-18208 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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 ...

How severe is CVE-2026-18208?

CVE-2026-18208 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-18208?

Check the references section above for vendor advisories and patch information. Affected products include: Redhat Build Of Keycloak.