CVE-2026-9801
Keycloak: keycloak: denial of service via malformed ldap password policy response
CVSS Score
4.9
EPSS Score
0.4%
EPSS Percentile
35th
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.
| CWE | CWE-1284 |
| Vendor | red hat |
| Product | red hat build of keycloak 26.4 |
| Published | May 28, 2026 |
| Last Updated | Jun 26, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
Red Hat / Red Hat build of Keycloak 26.4
All versions affected Red Hat / Red Hat build of Keycloak 26.4
All versions affected Red Hat / Red Hat build of Keycloak 26.4
All versions affected Red Hat / Red Hat build of Keycloak 26.4.13
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6.3
All versions affected References
access.redhat.com: https://access.redhat.com/errata/RHSA-2026:25097 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:25098 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:30049 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:30050 access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-9801 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2482473
Credits
Red Hat would like to thank Seongkuk Park for reporting this issue.