---
id: CVE-2026-16100
title: A flaw was found in the user-event metrics recording of Keycloak
summary: >-
  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-s…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-770
  - CWE-770
vendor: redhat
product: build_of_keycloak
affected:
  - 'build_of_keycloak >= 26.6, < 26.6.5'
patched:
  - build_of_keycloak 26.6.5
published: '2026-08-05'
updated: '2026-08-31'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-16100'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:50848'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:50849'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2026-16100'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2501730'
    label: secalert@redhat.com
tags:
  - nvd
epss: 0.00404
epssPercentile: 0.34466
ingestedAt: '2026-08-31T13:08:32.850Z'
---

## Overview

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.

## Affected

- `build_of_keycloak >= 26.6, < 26.6.5`

## Remediation

Upgrade past the affected range:

- `build_of_keycloak 26.6.5`