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Fencer Vulns
medium 6.5

CVE-2026-37979 json

Keycloak: keycloak: information disclosure via oidc token introspection endpoint audience bypass

published 2026-05-19 5 mo ago modified 2026-10-29 10 d ago also BIT-keycloak-2026-37979 , EUVD-2026-30887 , GHSA-4x37-hw65-52w8

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.keycloak:keycloak-services 26.6.2
  • bitnami keycloak 26.4.12
  • Red Hat Red Hat build of Keycloak 26.4 26.4-17, 26.4.12-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-37979 updated cvss 6.5

keycloak: Keycloak: Information disclosure via OIDC token introspection endpoint audience bypass

  • Red Hat build of Keycloak 26.4 rhbk/keycloak-rhel9 26.4-17, rhbk/keycloak-rhel9-operator 26.4-17, rhbk/keycloak-operator-bundle 26.4.12-1
    fixed: vendor fix RHSA-2026:19597
  • Red Hat build of Keycloak 26.4.12
    fixed: vendor fix RHSA-2026:19596

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
OSV 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-services
<26.6.2
26.6.2
bitnami keycloak
>=26.4.0, <26.4.12
26.4.12

Affected products

  • Red Hat Red Hat build of Keycloak 26.4
  • Red Hat Red Hat build of Keycloak 26.4.12

Classification

Weakness
  • CWE-639 Authorization Bypass Through User-Controlled Key
  • CWE-284 Improper Access Control

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.