What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-03-23 · updated 2026-06-17
• Weakness: CWE-79

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 .

Affected products

• typo3: from 10.0.0 before 10.4.14; from 11.0.0 before 11.1.1 — fixed in 10.4.14, 11.1.1

How to fix

Upgrade to a fixed version: typo3 10.4.14, 11.1.1. Check the vendor advisory for mitigations.

References

• https://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-fjh3-g8gq-9q92
• https://packagist.org/packages/typo3/cms-backend
• https://typo3.org/security/advisory/typo3-core-sa-2021-007
• https://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-fjh3-g8gq-9q92
• https://packagist.org/packages/typo3/cms-backend
• https://typo3.org/security/advisory/typo3-core-sa-2021-007

Get alerted when CVE-2021-21340 or the next vulnerability affects your stack