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

Quick answers

Is CVE-2021-21340 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2021-21340 being exploited in the wild.

How severe is CVE-2021-21340?

Low severity, with a CVSS score of 3.1, published 23 March 2021.

Which products and versions are affected?

typo3/cms (Packagist) ECOSYSTEM:introduced=10.0.0,fixed=10.4.14; typo3/cms-backend (Packagist) ECOSYSTEM:introduced=10.0.0,fixed=10.4.14; typo3/cms-core (Packagist) ECOSYSTEM:introduced=10.0.0,fixed=10.4.14.

Is there a fix for CVE-2021-21340?

Yes. typo3/cms (Packagist): upgrade to 10.4.14 or later; typo3/cms-backend (Packagist): upgrade to 10.4.14 or later; typo3/cms-core (Packagist): upgrade to 10.4.14 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Am I affected by CVE-2021-21340?

Check whether you run typo3/cms (Packagist), typo3/cms-backend (Packagist) or typo3/cms-core (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

• typo3/cms (Packagist): upgrade to 10.4.14 or later

  composer require typo3/cms:^10.4.14

• typo3/cms-backend (Packagist): upgrade to 10.4.14 or later

  composer require typo3/cms-backend:^10.4.14

• typo3/cms-core (Packagist): upgrade to 10.4.14 or later

  composer require typo3/cms-core:^10.4.14

Affected products

• typo3/cms (Packagist) ECOSYSTEM:introduced=10.0.0,fixed=10.4.14
• typo3/cms-backend (Packagist) ECOSYSTEM:introduced=10.0.0,fixed=10.4.14
• typo3/cms-core (Packagist) ECOSYSTEM:introduced=10.0.0,fixed=10.4.14

Identifiers

• CVE-2021-21340
• GHSA-fjh3-g8gq-9q92