CVE-2026-1035

Summary

A flaw was found in the Keycloak server during refresh token processing, specifically in the TokenManager class responsible for enforcing refresh token reuse policies. When strict refresh token rotation is enabled, the validation and update of refresh token usage are not performed atomically. This allows concurrent refresh requests to bypass single-use enforcement and issue multiple access tokens from the same refresh token. As a result, Keycloak’s refresh token rotation hardening can be undermined.

Affected Software

VendorProductVersion RangeStatus
Red HatRed Hat build of Keycloak 26.426.4.11-1 < *unaffected
Red HatRed Hat build of Keycloak 26.426.4-14 < *unaffected
Red HatRed Hat build of Keycloak 26.426.4-14 < *unaffected

Weaknesses

  • CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

Workarounds

To mitigate this issue, configure the refreshTokenMaxReuse policy in Keycloak to a value greater than zero. This prevents the race condition by allowing a limited number of reuses for refresh tokens, thereby maintaining the integrity of the Refresh Token Rotation hardening measure. Consult Keycloak documentation for specific configuration instructions. Changes to Keycloak configuration typically require a service restart or redeployment to take effect.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References