CVE-2026-11800

Summary

A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation.

Affected Software

VendorProductVersion RangeStatus
Red HatRed Hat build of Keycloak 26.626.6.4-2 < *unaffected
Red HatRed Hat build of Keycloak 26.626.6-8 < *unaffected
Red HatRed Hat build of Keycloak 26.626.6-8 < *unaffected

Weaknesses

  • CWE-347: Improper Verification of Cryptographic Signature

ADP Enrichment

CISA ADP Vulnrichment

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

org.keycloak:keycloak-services: Keycloak: Authentication bypass via JWT algorithm confusion

Additional References

References