CVE-2021-21340 Cross-Site Scripting in Content Preview

What is CVE-2021-21340?

CVE-2021-21340 is a medium-severity cross-site scripting vulnerability in Typo3 Typo3, published on 23 Mar 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 10.4.14, 11.1.1 it has been discovered that database fields used as _descriptionColumn_ are vulnerable to cross-site scripting when their content gets previewed. A valid backend user account is needed to exploit this vulnerability. This is fixed in versions 10.4.14, 11.1.1 .

Weakness: CWE-79

Which versions are affected by CVE-2021-21340?

13 open source packages ship an affected version, including typo3/cms, typo3 and typo3/cms-backend. It affects 1 product.

Products include Typo3 Typo3.

How do I fix CVE-2021-21340?

Upgrade typo3/cms to a fixed version for your release line: 10.4.14 or 11.1.1.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2021-21340 being exploited?

There is no known exploitation of CVE-2021-21340 in the wild and no public exploit code.

Other vulnerabilities in Typo3 Typo3

• CVE-2009-0258 Indexed Search Engine for TYPO3 Command Execution via Metacharacter Injection Critical 10.0
• CVE-2011-3583 Typo3 SQL injection due to faulty prepared statements Critical 9.8
• CVE-2011-4628 Typo3 Authentication Bypass Critical 9.8
• CVE-2023-24814 Persisted Cross-Site Scripting in Frontend Rendering in typo3 High 8.8
• CVE-2021-41113 Cross-Site-Request-Forgery in Backend URI Handling in Typo3 High 8.8

All Typo3 Typo3 vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-typo3-2021-21340, GHSA-fjh3-g8gq-9q92.