CVE-2026-9801
Keycloak Vulnerable to Improper Validation of Specified Quantity in Input
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.
How to fix CVE-2026-9801
To remediate CVE-2026-9801, upgrade the affected package to a fixed version below.
- —upgrade to 26.6.3 or later
Is CVE-2026-9801 being exploited?
Low — EPSS is 0.5%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 26.6.3
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM4.9 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H |