CVE-2026-9801

Summary

A flaw was found in Keycloak. A remote attacker with high privileges, such as a realm administrator configuring a malicious Lightweight Directory Access Protocol (LDAP) server or an attacker compromising an upstream LDAP server, could exploit this vulnerability. By sending a malformed LDAP password policy response during a password authentication request, the attacker can trigger an OutOfMemoryError. This causes the Keycloak Java Virtual Machine (JVM) to terminate, leading to a denial of service (DoS) for all realms on the affected node.

Affected Software

VendorProductVersion RangeStatus
Red HatRed Hat build of Keycloak 26.426.4.13-1 < *unaffected
Red HatRed Hat build of Keycloak 26.426.4-19 < *unaffected
Red HatRed Hat build of Keycloak 26.426.4-19 < *unaffected
Red HatRed Hat build of Keycloak 26.626.6.3-3 < *unaffected
Red HatRed Hat build of Keycloak 26.626.6-6 < *unaffected
Red HatRed Hat build of Keycloak 26.626.6-6 < *unaffected

Weaknesses

  • CWE-1284: Improper Validation of Specified Quantity in Input

Workarounds

To mitigate this vulnerability, ensure that Keycloak's LDAP user-storage providers are configured to connect only to trusted and secure LDAP servers. Avoid configuring LDAP federation with unverified or potentially malicious LDAP endpoints. Additionally, always use TLS for LDAP connections to prevent Man-in-the-Middle attacks. If an upstream LDAP server is compromised, it should be isolated and secured immediately.

ADP Enrichment

CISA ADP Vulnrichment

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

References