# CVE-2021-21370: Cross-Site Scripting in Content Preview (CType menu)

Source: https://junglewise.ai/threats/cve-2021-21370-cross-site-scripting-in-content-preview-ctype-menu  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-03-23  
License: CC BY 4.0 with a link back

CVE-2021-21370 · Severity: low · CVSS 3.1 · Published 2021-03-23

Cross-Site Scripting in Content Preview (CType menu)

Technologies: [typo3/cms (Packagist)](https://junglewise.ai/threats/technologies/packagist-typo3-cms), [typo3/cms-backend (Packagist)](https://junglewise.ai/threats/technologies/typo3-cms-backend), [typo3/cms-core (Packagist)](https://junglewise.ai/threats/technologies/typo3-cms-core). Vendors: [Packagist](https://junglewise.ai/threats/vendors/packagist).

## Quick answers

**Is CVE-2021-21370 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-21370 being exploited in the wild.

**How severe is CVE-2021-21370?** 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=7.0.0,fixed=7.6.51; typo3/cms-core (Packagist) ECOSYSTEM:introduced=10.0.0,fixed=10.4.14.

**Is there a fix for CVE-2021-21370?** Yes. typo3/cms (Packagist): upgrade to 10.4.14 or later; typo3/cms-backend (Packagist): upgrade to 7.6.51 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-2021-21370?** 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

  ```sh
  composer require typo3/cms:^10.4.14
  ```

- typo3/cms-backend (Packagist): upgrade to 7.6.51 or later

  ```sh
  composer require typo3/cms-backend:^7.6.51
  ```

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

  ```sh
  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=7.0.0,fixed=7.6.51
- typo3/cms-core (Packagist) ECOSYSTEM:introduced=10.0.0,fixed=10.4.14

## Identifiers

- CVE-2021-21370
- GHSA-x7hc-x7fm-f7qh

## Related threats

- [The referrer enforcement introduced with TYPO3-CORE-SA-2020-006 became ineffective in TYPO3 v13.0, where TYPO3 CMS started](https://junglewise.ai/threats/cve-2026-19418-typo3-cms-broken-access-control-in-backend-and-install-tool)
- [TYPO3 CMS broken access control in Media Module](https://junglewise.ai/threats/cve-2026-49742-typo3-cms-broken-access-control-in-media-module)
- [TYPO3 CMS broken access control in Form Framework form_definition table](https://junglewise.ai/threats/cve-2026-49741-typo3-cms-broken-access-control-in-form-framework-form-definition)
- [TYPO3 CMS insecure deserialization in VariableFrontend and Registry](https://junglewise.ai/threats/cve-2026-49740-typo3-cms-insecure-deserialization-in-variablefrontend-and)
- [TYPO3 CMS path traversal in GeneralUtility::isAllowedAbsPath](https://junglewise.ai/threats/cve-2026-49738-typo3-cms-path-traversal-in-generalutility-isallowedabspath)