CVE-2026-9801
Keycloak: keycloak: denial of service via malformed ldap password policy response
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Keycloak: keycloak: denial of service via malformed ldap password policy response
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.
- Record
CVE-2026-9801- CVSS 3.1
- 4.9 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-1284
- Updated
- 2026-11-02
EUVDEUVD-2026-32718
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.
- Record
EUVD-2026-32718- CVSS 3.1
- 4.9 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-f6r7-6w34-x2gp
Keycloak Vulnerable to Improper Validation of Specified Quantity in Input
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.
- Record
GHSA-f6r7-6w34-x2gp- CVSS 3.1
- 4.9 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-1284
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-9801- CVSS 3.1
- 4.9 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-1284
- Updated
- 2026-11-02
OSVGHSA-f6r7-6w34-x2gp
Keycloak Vulnerable to Improper Validation of Specified Quantity in Input
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.
- Record
GHSA-f6r7-6w34-x2gp- CVSS 3.1
- 4.9 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-1284
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
org.keycloak:keycloak-ldap-federationMaven |
before 26.6.3 | 26.6.3 |
org.keycloak:keycloak-ldap-federationMaven |
before 26.6.3, plus listed versions 1.0-beta-41.0-final1.0-rc-11.0-rc-21.0.1.Final Show 45 moreShow less1.0.2.Final1.0.3.Final1.0.4.Final1.0.5.Final1.1.0.Beta11.1.0.Beta21.1.0.Final1.1.1.Final1.2.0.Beta11.2.0.CR11.2.0.Final1.3.0.Final1.3.1.Final1.4.0.Final1.5.0-Final1.5.0.Final1.5.1.Final1.6.0.Final1.6.1.Final1.7.0.CR11.7.0.Final1.8.0.Alpha11.8.0.CR11.8.0.CR21.8.0.CR31.8.0.Final1.8.1.Final1.9.0.CR11.9.0.Final1.9.1.Final1.9.2.Final1.9.3.Final1.9.4.Final1.9.5.Final1.9.7.Final1.9.8.Final10.0.010.0.110.0.211.0.011.0.111.0.211.0.312.0.012.0.1 |
26.6.3 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-9801 is a medium vulnerability (CVSS 4.9) in Red Hat Build Of Keycloak 26.4, published May 28, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.48%, the 41st percentile. Fixed in org.keycloak:keycloak-ldap-federation 26.6.3.
References
Left out here: 167 versions. The JSON record has them.