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.

Published: 2026-05-28 Last update: 2026-06-10 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-9801 is rated Low Risk (39.3/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.33%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-9801

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-11 0.25% 0.33% +0.08%
2 2026-06-04 0.28% 0.25% -0.04%
3 2026-05-28 — 0.28% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-9801

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.2 3.6 [email protected]

Weakness enumeration for CVE-2026-9801

GitHub Security Advisory for CVE-2026-9801

GHSA-f6r7-6w34-x2gp · Severity: medium — A flaw was found in Keycloak. A remote attacker with high privileges, such as a realm...

OS Trackers for CVE-2026-9801

vendor priority summary link
redhat medium — https://access.redhat.com/security/cve/CVE-2026-9801

Affected software / configurations for CVE-2026-9801

Vendor Product Version Raw CPE
redhat build_of_keycloak — cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:*

References for CVE-2026-9801

cvelogic Threat Intelligence