TYPO3 CMS - Broken Access Control in Backend and Install Tool

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-19418: 0.24% estimated exploitation activity in the next 30 days; percentile 15.43 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Problem 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 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…

Published by the source

1 Sep 2026, 21:31 UTC

Last modified by the source

1 Sep 2026, 21:55 UTC

Source last checked

26 Oct 2026, 14:53 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-68jx-f42c-7599

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-68jx-f42c-7599

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# Patch Next advisory brief: CVE-2026-19418

Advisory: TYPO3 CMS - Broken Access Control in Backend and Install Tool
IDs: CVE-2026-19418, GHSA-68jx-f42c-7599
Record: https://patchnext.com/advisories/cve-2026-19418 (revision 3, source checked 26 Oct 2026, 14:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: typo3/cms-backend 13.4.34; typo3/cms-core 14.3.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist typo3/cms-backend: affected >= 13.0.0, < 13.4.34; fixed in 13.4.34
- Packagist typo3/cms-core: affected >= 14.0.0, < 14.3.6; fixed in 14.3.6

## Suggested inspection (read-only)
- Packagist typo3/cms-backend: check the installed version with your package manager.
- Packagist typo3/cms-core: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on typo3/cms-backend, typo3/cms-core.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-68jx-f42c-7599 (OSV record GHSA-68jx-f42c-7599 lists affected ranges: Packagist typo3/cms-backend >=13.0.0 =14.0.0 <14.3.6 (fixed))
- Verified: https://github.com/advisories/GHSA-68jx-f42c-7599 (GitHub-reviewed advisory GHSA-68jx-f42c-7599 lists affected ranges: Packagist typo3/cms-backend >=13.0.0 =14.0.0 <14.3.6)

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