CVE-2026-9801

Keycloak: keycloak: denial of service via malformed ldap password policy response

MEDIUM
4.9
CVSS Score
Published: May 28, 2026 at 04:42 AM UTC
Updated: October 26, 2026 at 12:10 PM UTC
1 product affected across 1 vendorBuild of Keycloak

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Severity
MEDIUM4.9
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

All versions26.4
Vendor states this is fixed in 26.4-19 (unaffected)
Vendor states this is fixed in 26.4.13 (unaffected)
Vendor states this is fixed in 26.4.13-1 (unaffected)
Vendor states this is fixed in 26.6-6 (unaffected)
Vendor states this is fixed in 26.6.3 (unaffected)
Vendor states this is fixed in 26.6.3-3 (unaffected)

References (6)

VDB Entryx_refsource_REDHATMitigationVendor Advisory
Source: cverecord
https://access.redhat.com/security/cve/CVE-2026-9801
Issue Trackingx_refsource_REDHATVendor Advisory
Source: cverecord
https://bugzilla.redhat.com/show_bug.cgi?id=2482473
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:25098
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:25097
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:30049
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:30050

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.9MEDIUMredhat
Attack Vector
NETWORK
Complexity
LOW
Privileges
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-1284

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