--- title: "TYPO3-CORE-SA-2021-009: Cross-Site Scripting in Page Preview" url: "https://news.typo3.com/security/advisory/typo3-core-sa-2021-009" description: It has been discovered that TYPO3 CMS is vulnerable to cross-site scripting. image: "https://news.typo3.com/_assets/d1e01514e4c4a5b3147940fa2ec50682/Images/og-image-news.jpg" date: 2026-06-11 modified: 2026-06-11 categories: - "Developer & Technology" - TYPO3 CMS --- # TYPO3-CORE-SA-2021-009: Cross-Site Scripting in Page Preview - [Developer & Technology](https://news.typo3.com/article/category/developer-technology) - Security / [TYPO3 CMS](https://news.typo3.com/article/category/security/typo3-cms) TYPO3-CORE-SA-2021-009: Cross-Site Scripting in Page Preview ============================================================ 20 July 2021 ![A laptop screen displaying a list of security advisories](https://news.typo3.com/typo3temp/assets/_processed_/d/c/csm_security_blog_default_77f8e86036.webp) It has been discovered that TYPO3 CMS is vulnerable to cross-site scripting. - ![](https://news.typo3.com/typo3temp/assets/t3g/blog/gravatar/b8266fdc667b773926c59081862ab148.jpeg)[Oliver Hader](https://news.typo3.com/article/author/oliver-hader) - **Component Type:** TYPO3 CMS - **Subcomponent:** Page Preview (ext:viewpage) - **Release Date:** July 20, 2021 - **Vulnerability Type:** Cross-Site Scripting - **Affected Versions:** 9.0.0-9.5.27, 10.0.0-10.4.17, 11.0.0-11.3.0 - **Severity:** Medium - **Suggested CVSS:** [CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC](https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C&version=3.1) - **References:** [CVE-2021-32667](https://nvd.nist.gov/vuln/detail/CVE-2021-32667), [CWE-79](https://cwe.mitre.org/data/definitions/79.html) ### Problem Description Failing to properly encode *Page TSconfig* settings, the corresponding page preview module (*Web>View*) is vulnerable to persistent cross-site scripting. A valid backend user account is needed to exploit this vulnerability. ### Solution Update to TYPO3 versions 9.5.28, 10.4.18, 11.3.1 that fix the problem described. ### Credits Thanks to TYPO3 core merger Oliver Bartsch who reported and fixed the issue. ### General Advice Follow the recommendations that are given in the [TYPO3 Security Guide](https://docs.typo3.org/typo3cms/CoreApiReference/Security/Index.html#security). Please subscribe to the [typo3-announce](http://lists.typo3.org/cgi-bin/mailman/listinfo/typo3-announce) mailing list. ### General Note All security related code changes are tagged so that you can easily look them up in our [review system](https://review.typo3.org/#/q/status:merged+project:Packages/TYPO3.CMS+topic:security,n,z). ![](https://news.typo3.com/typo3temp/assets/t3g/blog/gravatar/cc7cba9757f98fbe05023a139119df74.jpeg) About the Author [Oliver Hader](https://news.typo3.com/article/author/oliver-hader) Core Developer at TYPO3 GmbH,Hof, Germany [Website](https://typo3.com)[Twitter](https://twitter.com/ohader)[LinkedIn](https://www.linkedin.com/in/oliverhader/)[Xing](https://www.xing.com/profile/Oliver_Hader) Oliver started to work with TYPO3 in 2005 and was fascinated by the product and its universe. Since 2007 he is member of the TYPO3 Core Team. After going back to university in 2014 for achieving a postgraduate master degree in internet web science, he is now researching on advanced web technology topics in general and for TYPO3 in particular. In his spare time, Oliver loves to go cycling cross-country in the uplands around Hof (Germany) in northern Bavaria - at the region where he's living as well. [More posts by this author](https://news.typo3.com/article/author/oliver-hader)