CVE-2026-9801: build of keycloak — Fix

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.

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CVSS v3.1 Score

4.9

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0044

Probability of exploitation

0.35%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1284 CWE-1284

Affected Products

Vendor	Product	Versions
redhat	build_of_keycloak	All

References

Advisories & Patches

https://access.redhat.com/security/cve/CVE-2026-9801 https://bugzilla.redhat.com/show_bug.cgi?id=2482473

Frequently Asked Questions

What is CVE-2026-9801? +

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. It has a CVSS v3.1 base score of 4.9 (MEDIUM).

How severe is CVE-2026-9801? +

CVE-2026-9801 has a CVSS v3.1 score of 4.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0044, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-9801? +

CVE-2026-9801 affects products from redhat, specifically: build_of_keycloak. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-9801? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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