CVE-2026-37979Network attack vector

Authenticated claim disclosure via missing audience validation

Published May 19, 2026 · Updated May 19, 2026

Improper access control in Red Hat build of Keycloak 26.4 releases before 26.4.12 allows remote authenticated users to read protected token claims. AccessTokenIntrospectionProvider returns transformed claims for a valid token without verifying that the authenticated client appears in its audience. A confidential client with valid realm credentials can introspect lightweight access tokens issued for other resource servers; integrity and availability are unaffected.

CVSS severity6.5
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Red Hat build of Keycloak 26.4 releases before 26.4.12 allows remote authenticated users to read protected token claims. AccessTokenIntrospectionProvider returns transformed claims for a valid token without verifying that the authenticated client appears in its audience. A confidential client with valid realm credentials can introspect lightweight access tokens issued for other resource servers; integrity and availability are unaffected.

The record

CVE
CVE-2026-37979
Published
May 19, 2026
Updated
May 19, 2026
Vendor
389 Directory Server
Product
Red Hat build of Keycloak
Classifications
CWE-284
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 19, 2026CVE publishedPublication date reported by the CVE source.
  2. May 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

389 Directory Server · Red Hat build of KeycloakAffected versions are unavailable in this record.

Published CVSS scores

6.5Red Hat, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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