GHSA-c5c9-8c6m-727v Cross-Site Scripting via Rich-Text Content

• Packagist typo3/cms-core: >= 7.0.0, < 7.6.53 → fixed in 7.6.53 • Packagist typo3/cms-core: >= 8.0.0, < 8.7.42 → fixed in 8.7.42 • Packagist typo3/cms-core: >= 10.0.0, < 10.4.19 → fixed in 10.4.19 • Packagist typo3/cms-core: >= 11.0.0, < 11.3.2 → fixed in 11.3.2 • Packagist typo3/cms-core: >= 9.0.0, < 9.5.29 → fixed in 9.5.29 • Packagist typo3/cms: >= 10.0.0, < 10.4.19 → fixed in 10.4.19 • Packagist typo3/cms: >= 11.0.0, < 11.3.2 → fixed in 11.3.2 • Packagist typo3/cms: >= 9.0.0, < 9.5.29 → fixed in 9.5.29 • Packagist typo3/cms: >= 8.0.0, < 8.7.42 → fixed in 8.7.42 • Packagist typo3/cms: >= 7.0.0, < 7.6.53 → fixed in 7.6.53

> ### Meta > * 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` (5.7) Problem 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_ 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_ - 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. 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. References • TYPO3-CORE-SA-2021-013