- Component Type: TYPO3 CMS
- Subcomponent: Content Preview Renderer (ext:backend)
- Release Date: March 16, 2021
- Vulnerability Type: Cross-Site Scripting
- Affected Versions: 7.0.0-7.6.50, 8.0.0-8.7.39, 9.0.0-9.5.16, 10.0.0-10.4.1, 11.0.0-11.1.0
- Severity: Medium
- Suggested CVSS: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C
- References: CVE-2021-21370, CWE-79
It has been discovered that content elements of type menu are vulnerable to cross-site scripting when their referenced items get previewed in the page module. A valid backend user account is needed to exploit this vulnerability.
The affected code is only executed if an extension is used that actually leverages the type menu. By default this is not available by the Core.
Update to TYPO3 versions 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1 that fix the problem described.
Thanks to TYPO3 contributor Oliver Bartsch who reported and fixed the issue.
All security related code changes are tagged so that you can easily look them up in our review system.