---
id: CVE-2026-19418
aliases:
  - GHSA-68jx-f42c-7599
title: TYPO3 CMS - Broken Access Control in Backend and Install Tool
summary: TYPO3 CMS - Broken Access Control in Backend and Install Tool
severity: high
cwe:
  - CWE-346
  - CWE-352
vendor: typo3
product: typo3/cms-backend
ecosystem: composer
affected:
  - 'typo3/cms-backend >= 13.0.0, < 13.4.34'
  - 'typo3/cms-core >= 14.0.0, < 14.3.6'
patched:
  - typo3/cms-backend 13.4.34
  - typo3/cms-core 14.3.6
published: '2026-09-01'
updated: '2026-09-01'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-68jx-f42c-7599'
references:
  - url: 'https://github.com/TYPO3/typo3/security/advisories/GHSA-68jx-f42c-7599'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-19418'
  - url: >-
      https://github.com/TYPO3/typo3/commit/4a75e862c589c85d795d7c65dcdc835f8f413efc
  - url: >-
      https://github.com/TYPO3/typo3/commit/a0e8ee06a40e959b9e7b06a4b1cb19d3a0d3dcf7
  - url: >-
      https://github.com/TYPO3/typo3/commit/ae0abd329d52285fe6e92804c3608820ad45e872
  - url: >-
      https://github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms-core/CVE-2026-19418.yaml
  - url: 'https://news.typo3.com/security/advisory/typo3-core-sa-2026-021'
  - url: 'https://typo3.org/security/advisory/typo3-core-sa-2020-006'
  - url: 'https://typo3.org/security/advisory/typo3-core-sa-2026-021'
  - url: 'https://github.com/advisories/GHSA-68jx-f42c-7599'
tags:
  - ghsa
  - composer
epss: 0.00213
epssPercentile: 0.11869
ingestedAt: '2026-09-01T21:32:41.261Z'
---

## Overview

### Problem
The referrer enforcement introduced with [TYPO3-CORE-SA-2020-006](https://news.typo3.com/security/advisory/typo3-core-sa-2020-006) ([CVE-2020-11069](https://www.cve.org/CVERecord?id=CVE-2020-11069)) became ineffective in TYPO3 v13.0, where TYPO3 CMS started serving the backend and Admin Tool applications from the site's main entry script instead of the dedicated typo3/ directory.

Whether a request originated from the backend or Install Tool itself was determined by comparing the referrer against the directory of the entry script, which since then is the site root. As a consequence, requests originating from any script running on one of the TYPO3 instance's own domains, such as a frontend page, were accepted by backend routes and Install Tool endpoints.

Attackers able to execute JavaScript on one of those domains, for instance by exploiting a cross-site scripting vulnerability, could invoke these endpoints via Fetch/XHR with the privileges of an authenticated victim's user session.

### Solution
Update to TYPO3 versions 13.4.34 LTS, 14.3.6 LTS that fix the problem described.

### Credits
Thanks to Hổ Cao Từ for reporting this issue, and to TYPO3 core & security team member Benjamin Franzke for fixing it.

## Affected packages

- `typo3/cms-backend >= 13.0.0, < 13.4.34`
- `typo3/cms-core >= 14.0.0, < 14.3.6`

## Remediation

Upgrade to a patched release:

- `typo3/cms-backend 13.4.34`
- `typo3/cms-core 14.3.6`