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CVE-2026-9801— Keycloak: keycloak: denial of service via malformed ldap password policy response

Quick assessment

Affected
Red Hat Red Hat build of Keycloak 26.4
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Keycloak是Keycloak开源的一种开源身份和访问管理解决方案。 Keycloak存在安全漏洞，该漏洞源于具有高权限的远程攻击者（如配置恶意LDAP服务器的领域管理员或攻击者破坏上游LDAP服务器）可通过在密码身份验证请求期间发送格式错误的LDAP密码策略响应，触发OutOfMemoryError，可能导致Keycloak Java虚拟机终止，从而导致受影响节点上所有领域的拒绝服务。

CVSS 4.9 · Medium EPSS 0.90% · P58

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 8

VendorProduct Version RangeStatus
Red Hat Red Hat build of Keycloak 26.4 26.4.13-1< * unaffected
26.4-19< * unaffected
26.4-19< * unaffected
Red Hat Red Hat build of Keycloak 26.4.13 any unaffected
Red Hat Red Hat build of Keycloak 26.6 26.6.3-3< * unaffected
26.6-6< * unaffected
26.6-6< * unaffected
Red Hat Red Hat build of Keycloak 26.6.3 any unaffected
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I. Basic Information for CVE-2026-9801

Vulnerability Information
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Vulnerability Title
Keycloak: keycloak: denial of service via malformed ldap password policy response
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1284
Source: CVE Program / CVE List V5
Vulnerability Title
Keycloak 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Keycloak是Keycloak开源的一种开源身份和访问管理解决方案。 Keycloak存在安全漏洞，该漏洞源于具有高权限的远程攻击者（如配置恶意LDAP服务器的领域管理员或攻击者破坏上游LDAP服务器）可通过在密码身份验证请求期间发送格式错误的LDAP密码策略响应，触发OutOfMemoryError，可能导致Keycloak Java虚拟机终止，从而导致受影响节点上所有领域的拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Red Hat Red Hat build of Keycloak 26.4 26.4.13-1 ~ * cpe:/a:redhat:build_keycloak:26.4::el9
Red Hat Red Hat build of Keycloak 26.4 26.4-19 ~ * cpe:/a:redhat:build_keycloak:26.4::el9
Red Hat Red Hat build of Keycloak 26.4 26.4-19 ~ * cpe:/a:redhat:build_keycloak:26.4::el9
Red Hat Red Hat build of Keycloak 26.4.13 - cpe:/a:redhat:build_keycloak:26.4::el9
Red Hat Red Hat build of Keycloak 26.6 26.6.3-3 ~ * cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat Red Hat build of Keycloak 26.6 26.6-6 ~ * cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat Red Hat build of Keycloak 26.6 26.6-6 ~ * cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat Red Hat build of Keycloak 26.6.3 - cpe:/a:redhat:build_keycloak:26.6::el9

II. Public POCs for CVE-2026-9801

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III. Intelligence Information for CVE-2026-9801

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Vendor Advisories for CVE-2026-9801 (3)

Other References for CVE-2026-9801 (3)

Same Patch Batch · Red Hat · 2026-05-28 · 14 CVEs total

CVE-2026-4408 9.0 CRITICAL Samba: remote code execution in samr
CVE-2026-9804 7.7 HIGH Kubevirt: kubevirt: vmexport directory symlink escape enables exporter pod file read
CVE-2026-9795 7.3 HIGH Keycloak: keycloak: privilege escalation via improper scope mapping enforcement
CVE-2026-44604 7.0 HIGH Rpm: command injection in rpmuncompress dountar() via unescaped archive top-level director
CVE-2026-9802 6.8 MEDIUM Keycloak: keycloak: unauthorized account access via replayed refresh tokens after cluster
CVE-2026-9792 6.5 MEDIUM Keycloak: keycloak: security restriction bypass allows unauthorized ropc token acquisition
CVE-2026-9796 6.5 MEDIUM Keycloak: keycloak: privilege escalation via time-of-check to time-of-use (toctou) vulnera
CVE-2026-9793 5.9 MEDIUM Keycloak: keycloak: security policy bypass in jwe-encrypted request object processing
CVE-2026-9794 5.3 MEDIUM Keycloak: keycloak: information disclosure via saml ecp endpoint
CVE-2026-9803 5.3 MEDIUM Keycloak: keycloak: denial of service via malformed authorization header
CVE-2026-9791 4.3 MEDIUM Keycloak-rhel9: organization data leak after feature disabled in keycloak
CVE-2026-9798 4.3 MEDIUM Keycloak: keycloak: brute-force protection bypass in ciba flow
CVE-2026-10028 4.3 MEDIUM Glib-networking: infinite loop in glib-networking gnutls backend allows remote denial of s

IV. Related Vulnerabilities

Same product: Red Hat build of Keycloak 26.4
Same vendor: Red Hat
Same weakness: CWE-1284

V. Comments for CVE-2026-9801

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