GHSA-4f2f-jr2m-j7p4

Duplicate Advisory: TYPO3-CORE-SA-2026-021: Broken Access Control in Backend and Install Tool

Published

2026-08-11

Modified

2026-09-01

Sources

github-advisory

Summary

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-68jx-f42c-7599. This link is maintained to preserve external references. ## Original Description The referrer enforcement introduced with TYPO3-CORE-SA-2020-006 (CVE-2020-11069) became ineffective in TYPO3 v13.0, where TYPO3 CMS started serving the backend and Install 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. This issue affects TYPO3 CMS versions 13.0.0-13.4.33 and 14.0.0-14.3.5.

Affected packages

Remediation: Upgrade to 13.4.34 or later.

References

• https://github.com/advisories/GHSA-4f2f-jr2m-j7p4