Cyber Resilience

CVE-2026-9801

MediumUpdated

Published: 28 May 2026

Published
28 May 2026
Modified
10 June 2026
KEV Added
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Patch
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CVSS Score v3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.0033 56.0th percentile
Risk Priority 10 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-9801 is a medium-severity Improper Validation of Specified Quantity in Input (CWE-1284) vulnerability in Redhat Build Of Keycloak. Its CVSS base score is 4.9 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked in the top 44.0% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

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…

more

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.

CWE(s)
CWE-1284

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
Why these techniques?

Malformed LDAP response triggers JVM OOM crash, directly enabling application exploitation for endpoint DoS.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

Affected Assets

redhat
build of keycloak
all versions

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References