CVE-2026-18208

MEDIUM
MEDIUM Priority: 0.03 BB Relevance: 63/100
Published: 2026-07-31 Modified: 2026-11-06 First seen: 2026-11-06 Status: active

Attack Surface

Network Low Complexity No Interaction Conf. Impact

CVSS Vector Breakdown

AV: Network
AC: Low
PR: Low
UI: None
S: Unchanged
C: High
I: None
A: None

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.

Weakness Classification (1)

Affected Software (1)

VendorProductVersion
redhat build_of_keycloak -

References & Advisories (4)

https://access.redhat.com/errata/RHSA-2026:95761
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:95762
vendor-advisory x_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2508304
issue-tracking x_refsource_REDHAT

Bug Bounty Relevance

63 / 100
✓ Network accessible
✓ Low complexity
✓ No user interaction

CVSS Score

6.5 / 10.0 v3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS — Exploitation Probability

0.41%
Raw Score 0.004070
Percentile 35.6%
Date 2026-11-13

EPSS Trend

2026-11-13
0.00407
2026-11-12
0.00407
2026-11-10
0.00407
2026-11-09
0.00407
2026-11-08
0.00407
2026-11-07
0.00407
2026-11-06
0.00341
2026-11-05
0.00341

Intelligence Sources

mitre ref →
nvd ref →