# CVE-2026-9801: Keycloak denial of service via malformed LDAP password policy response

Source: https://junglewise.ai/threats/cve-2026-9801-keycloak-denial-of-service-via-malformed-ldap-password-policy  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-28. Updated: 2026-07-01  
License: CC BY 4.0 with a link back

CVE-2026-9801 · Severity: medium · CVSS 4.9 · Published 2026-05-28

Keycloak, a popular identity and access management solution, is vulnerable to a denial-of-service attack when integrated with LDAP directory services. An attacker with administrative privileges or control over a connected LDAP server can send a specially crafted response that causes the Keycloak server to run out of memory and crash. This results in a complete service outage for all users and applications relying on the affected Keycloak instance for authentication.

Technologies: [Keycloak](https://junglewise.ai/threats/technologies/keycloak), [org.keycloak:keycloak-ldap-federation (Maven)](https://junglewise.ai/threats/technologies/org-keycloak-keycloak-ldap-federation), [Red Hat build of Keycloak](https://junglewise.ai/threats/technologies/red-hat-build-of-keycloak). Vendors: [Keycloak](https://junglewise.ai/threats/vendors/keycloak), [Maven](https://junglewise.ai/threats/vendors/maven), [Red Hat](https://junglewise.ai/threats/vendors/red-hat).

## Quick answers

**Is CVE-2026-9801 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-9801 being exploited in the wild.

**How severe is CVE-2026-9801?** Medium severity, with a CVSS score of 4.9, published 28 May 2026.

**Which products and versions are affected?** Keycloak < 26.6.3; Keycloak-Ldap-Federation < 26.6.3; org.keycloak:keycloak-ldap-federation (Maven) < 26.6.3, ECOSYSTEM:introduced=0,fixed=26.6.3; Red Hat build of Keycloak 26.4, 26.6.

**Is there a fix for CVE-2026-9801?** Yes. org.keycloak:keycloak-ldap-federation (Maven): upgrade to 26.6.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-9801 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-9801?** Check whether you run Keycloak, Keycloak-Ldap-Federation, org.keycloak:keycloak-ldap-federation (Maven) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- org.keycloak:keycloak-ldap-federation (Maven): upgrade to 26.6.3 or later

  ```sh
  # set org.keycloak:keycloak-ldap-federation to 26.6.3 in your pom.xml or build.gradle
  ```


## Technical details

A vulnerability exists in the Keycloak LDAP federation provider (org.keycloak:keycloak-ldap-federation) due to improper validation of specified quantities in input (CWE-1284). A remote attacker with high privileges (such as a realm administrator) or an attacker who has compromised an upstream LDAP server can exploit this by sending a malformed LDAP password policy response during an authentication request. This malformed input triggers an OutOfMemoryError within the Java Virtual Machine (JVM), causing the process to terminate and resulting in a denial of service for all realms on the node. The issue is fixed in Keycloak version 26.6.3.

## Affected products

- Keycloak Keycloak < 26.6.3
- Keycloak keycloak-ldap-federation < 26.6.3
- Red Hat Red Hat build of Keycloak 26.4, 26.6

## Identifiers

- CVE-2026-9801
- GHSA-f6r7-6w34-x2gp

## Timeline

- 2026-05-28: disclosed
- 2026-05-28: advisory
- 2026-06-10: patched: Red Hat security advisory issued

## References

- [https://access.redhat.com/security/cve/CVE-2026-9801](https://access.redhat.com/security/cve/CVE-2026-9801)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2482473](https://bugzilla.redhat.com/show_bug.cgi?id=2482473)
- [https://access.redhat.com/errata/RHSA-2026:25098](https://access.redhat.com/errata/RHSA-2026:25098)
- [https://access.redhat.com/errata/RHSA-2026:25097](https://access.redhat.com/errata/RHSA-2026:25097)
- [https://access.redhat.com/errata/RHSA-2026:30049](https://access.redhat.com/errata/RHSA-2026:30049)

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- [Keycloak Dynamic Client Registration privilege escalation](https://junglewise.ai/threats/cve-2026-96547-a-flaw-was-found-in-the-dynamic-client-registration-component-of)