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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.keycloak:keycloak-ldap-federation | < 26.6.3 | 26.6.3 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-9801
- https://github.com/keycloak/keycloak/issues/49434
- https://github.com/keycloak/keycloak/pull/49514
- https://github.com/keycloak/keycloak/commit/2c4fe42235ba8c265b1da3a30541a270d5bd8c39
- https://access.redhat.com/errata/RHSA-2026:25097
- https://access.redhat.com/errata/RHSA-2026:25098
- https://access.redhat.com/errata/RHSA-2026:30049
- https://access.redhat.com/errata/RHSA-2026:30050
- https://access.redhat.com/security/cve/CVE-2026-9801
- https://bugzilla.redhat.com/show_bug.cgi?id=2482473
- https://github.com/keycloak/keycloak
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-1284- Platform
- Java / Kotlin (Maven)
- Package
org.keycloak:keycloak-ldap-federation- Disclosed
- 28.05.2026
- Updated
- 11.10.2026 12:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-f6r7-6w34-x2gp - CC BY 4.0
Vulnerability history: org.keycloak:keycloak-ldap-federation
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 5
- First → latest
- 11.2023 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 3
- Low 2
Disclosures per year
- 2023: 1
- 2024: 1
- 2025: 2
- 2026: 1
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Keycloak Vulnerable to Improper Validation of Specified Quantity in Input this entry
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