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Description

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.

PUBLISHED Reserved 2026-05-28 | Published 2026-05-28 | Updated 2026-05-30 | Assigner redhat




MEDIUM: 4.9CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Problem types

Improper Validation of Specified Quantity in Input

Product status

Default status
affected

Timeline

2026-05-28:Reported to Red Hat.
2026-05-28:Made public.

Credits

Red Hat would like to thank Seongkuk Park for reporting this issue.

References

access.redhat.com/security/cve/CVE-2026-9801 vdb-entry

bugzilla.redhat.com/show_bug.cgi?id=2482473 (RHBZ#2482473) issue-tracking

cve.org (CVE-2026-9801)

nvd.nist.gov (CVE-2026-9801)

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