---
id: CVE-2026-103884
title: A flaw was found in the X.509 client certificate authenticator of Keycloak
summary: >-
  A flaw was found in the X.509 client certificate authenticator of Keycloak.
  When CRL Distribution Point checking is enabled, the server fails to properly
  validate the file paths provided in a client certificate. An attacker can
  provide a…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H'
cwe:
  - CWE-22
vendor: Red Hat
product: keycloak-services
affected:
  - keycloak-services (all versions)
  - rhbk/keycloak-rhel9 (all versions)
  - keycloak-services
published: '2026-10-01'
updated: '2026-10-01'
sourceUpdated: '2026-10-01T20:36:15.187'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-103884'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-103884'
    label: secalert@redhat.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-103884.json
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-103884'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-103884'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-01T18:02:05.858472Z'
ingestedAt: '2026-10-01T18:55:42.368Z'
epss: 0.0023
epssPercentile: 0.13817
---

## Overview

A flaw was found in the X.509 client certificate authenticator of Keycloak. When CRL Distribution Point checking is enabled, the server fails to properly validate the file paths provided in a client certificate. An attacker can provide a specially crafted certificate that causes the server to attempt to read sensitive files from the local system or exhaust memory by loading extremely large files, potentially leading to information disclosure or a system crash.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Build of Keycloak, Red Hat Single Sign-On 7 · no fix planned: Red Hat Single Sign-On 7, Red Hat Build of Keycloak · updated 2026-10-02 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-103884.json)