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CVE-2026-16100— Keycloak-services: keycloak-services: unbounded metric cardinality in user event metrics via request-controlled error text

Quick assessment

Affected
Red Hat Red Hat build of Keycloak 26.6
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 Keycloak是Keycloak组织开源的一款身份认证与权限管理软件。 Keycloak存在安全漏洞，该漏洞源于用户事件指标记录中错误处理不当，当指标启用时，系统将失败账户操作的原始错误消息作为Prometheus指标标签，由于这些错误消息可包含用户提供的输入，经过身份验证的用户可创建大量唯一指标条目，最终耗尽系统内存，导致服务崩溃或不可用。

CVSS 6.5 · Medium EPSS 0.55% · P44

Affected Version Matrix 9

VendorProduct Version RangeStatus
Red Hat Red Hat build of Keycloak 26.6 26.6.5-1< * unaffected
26.6-11< * unaffected
26.6-11< * unaffected
Red Hat Red Hat build of Keycloak 26.6.5 any unaffected
any unaffected
any unaffected
Red Hat Red Hat Data Grid 8 any unaffected
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack any unaffected
Red Hat Red Hat Single Sign-On 7 any unaffected
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I. Basic Information for CVE-2026-16100

Vulnerability Information
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Vulnerability Title
Keycloak-services: keycloak-services: unbounded metric cardinality in user event metrics via request-controlled error text
Source: CVE Program / CVE List V5
Vulnerability Description
A flaw was found in the user-event metrics recording of Keycloak. When metrics are enabled, the system records raw error messages from failed account operations as Prometheus metric labels. Because these error messages can include user-supplied input like nonexistent client IDs, an authenticated user can create a massive number of unique metric entries, eventually exhausting system memory and causing the service to crash or become unavailable.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
Keycloak 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Keycloak Keycloak是Keycloak组织开源的一款身份认证与权限管理软件。 Keycloak存在安全漏洞，该漏洞源于用户事件指标记录中错误处理不当，当指标启用时，系统将失败账户操作的原始错误消息作为Prometheus指标标签，由于这些错误消息可包含用户提供的输入，经过身份验证的用户可创建大量唯一指标条目，最终耗尽系统内存，导致服务崩溃或不可用。
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 26.6 26.6.5-1 ~ * cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat Red Hat build of Keycloak 26.6 26.6-11 ~ * cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat Red Hat build of Keycloak 26.6 26.6-11 ~ * cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat Red Hat build of Keycloak 26.6.5 - cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat Red Hat build of Keycloak 26.6.5 - cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat Red Hat build of Keycloak 26.6.5 - cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat Red Hat Data Grid 8 - cpe:/a:redhat:jboss_data_grid:8
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack - cpe:/a:redhat:jbosseapxp
Red Hat Red Hat Single Sign-On 7 - cpe:/a:redhat:red_hat_single_sign_on:7

II. Public POCs for CVE-2026-16100

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III. Intelligence Information for CVE-2026-16100

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Vendor Advisories for CVE-2026-16100 (4)

Same Patch Batch · Red Hat · 2026-08-05 · 11 CVEs total

CVE-2026-10059 9.1 CRITICAL Cluster-curator-controller: cluster-curator-controller: namespace admin can escalate to cl
CVE-2026-10090 9.0 CRITICAL Multicluster-operators-subscription: multicluster-operators-subscription: namespace edit u
CVE-2026-15572 8.8 HIGH Keycloak-services: keycloak-services: dcr protocol mapper type-swap policy bypass allows p
CVE-2026-15573 8.1 HIGH Keycloak-services: keycloak-services: authorization bypass via unnormalized uri matching i
CVE-2026-16102 8.1 HIGH Keycloak-services: keycloak-services: default dcr policy allows role forgery via user prop
CVE-2026-16443 7.4 HIGH Keycloak-services: keycloak-services: saml broker metadata import disables response signat
CVE-2026-16442 7.4 HIGH Keycloak-services: keycloak-services: saml idp-initiated broker login bypasses link-only r
CVE-2026-49331 6.5 MEDIUM Openshift/oauth-proxy: openshift/oauth-proxy: unauthenticated identity header injection on
CVE-2026-44605 5.5 MEDIUM Rpm: heap buffer overflow in ndb slot table parsing
CVE-2026-16071 5.4 MEDIUM Keycloak-services: keycloak-services: ldap entry-dn user search bypasses configured users

IV. Related Vulnerabilities

Same product: Red Hat build of Keycloak 26.6
Same vendor: Red Hat
Same weakness: CWE-770

V. Comments for CVE-2026-16100

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