--- title: "TYPO3-CORE-SA-2021-013: Cross-Site Scripting via Rich-Text Content" url: "https://news.typo3.com/security/advisory/typo3-core-sa-2021-013" 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-2021-013: Cross-Site Scripting via Rich-Text Content - [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-2021-013: Cross-Site Scripting via Rich-Text Content ================================================================== 10 August 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:** Content Rendering, HTML Parser (ext:frontend, ext:core) - **Release Date:** August 10, 2021 - **Vulnerability Type:** Cross-Site-Scripting - **Affected Versions:** 7.0.0-7.6.52 ELTS, 8.0.0-8.7.41 ELTS, 9.0.0-9.5.28, 10.0.0-10.4.18, 11.0.0-11.3.1 - **Severity:** Medium - **Suggested CVSS:** [CVSS:3.1/AV:N/AC:L/PR:N/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:N/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C&version=3.1) - **References:** [CVE-2021-32768](https://nvd.nist.gov/vuln/detail/CVE-2021-32768), [CWE-79](https://cwe.mitre.org/data/definitions/79.html) ### Problem Description Failing to properly parse, sanitize and encode malicious rich-text content, the content rendering process in the website frontend is vulnerable to cross-site scripting. Corresponding rendering instructions via TypoScript functionality [*HTMLparser*](https://docs.typo3.org/m/typo3/reference-typoscript/10.4/en-us/Functions/Htmlparser.html) do not consider all potentially malicious HTML tag & attribute combinations per default. In addition, the lack of comprehensive default node configuration for rich-text fields in the backend user interface fosters this malfunction. In default scenarios, a valid backend user account is needed to exploit this vulnerability. In case custom plugins used in the website frontend accept and reflect rich-text content submitted by users, no authentication is required. ### Solution Update to TYPO3 versions 7.6.53 ELTS, 8.7.42 ELTS, 9.5.29, 10.4.19, 11.3.2 that fix the problem described above. Custom package [*typo3/html-sanitizer*](https://github.com/TYPO3/html-sanitizer) - based on allow-lists only - takes care of sanitizing potentially malicious markup. The default behavior is based on safe and commonly used markup - however, this can be extended or restricted further in case it is necessary for individual scenarios. During the frontend rendering process, sanitization is applied to the default TypoScript path *lib.parseFunc*, which is implicitly used by the Fluid view-helper instruction *f:format.html*. Rich-text data persisted using the backend user interface is sanitized as well. Implementation details are explained in corresponding [ChangeLog documentation](https://docs.typo3.org/c/typo3/cms-core/master/en-us/Changelog/9.5.x/Important-94484-IntroduceHTMLSanitizer.html). ### Credits Thanks to Benjamin Stiber, Gert-Jan Jansma, Gábor Ács-Kurucz, Alexander Kellner, Richie Lee, Nina Rösch who reported this issue, and to TYPO3 security team member Oliver Hader, as well as TYPO3 contributor Susanne Moog who 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)