TYPO3-CORE-SA-2021-014: Cross-Site-Request-Forgery in Backend URI Handling

Categories: Development, Security Created by Oliver Hader
It has been discovered that TYPO3 CMS is vulnerable to cross-site-request-forgery.

Problem Description

It has been discovered that the new TYPO3 v11 feature that allows users to create and share deep links in the backend user interface is vulnerable to cross-site-request-forgery.

The impact is the same as described in TYPO3-CORE-SA-2020-006 (CVE-2020-11069). However, it is not limited to the same site context and does not require the attacker to be authenticated. In a worst case scenario, the attacker could create a new admin user account to compromise the system.

To successfully carry out an attack, an attacker must trick his victim to access a compromised system. The victim must have an active session in the TYPO3 backend at that time.

The following Same-Site cookie settings in $GLOBALS[TYPO3_CONF_VARS][BE][cookieSameSite] are required for an attack to be successful:

  • SameSite=strict: malicious evil.example.org invoking TYPO3 application at www.example.org
  • SameSite=lax or none: malicious evil.com invoking TYPO3 application at example.org


Update your instance to TYPO3 version 11.5.0 which addresses the problem described.


Thanks to Richie Lee who reported this issue and to TYPO3 core & security team members Benni Mack and Oliver Hader who fixed the issue.

General Advice

Follow the recommendations that are given in the TYPO3 Security Guide. Please subscribe to the typo3-announce mailing list.

General Note

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