Persisted Cross-Site Scripting in Frontend Rendering in typo3

TYPO3 is a free and open source Content Management Framework released under the GNU General Public License. In affected versions the TYPO3 core component GeneralUtility::getIndpEnv() uses the unfiltered server environment variable PATH_INFO, which allows attackers to inject malicious content. In combination with the TypoScript setting config.absRefPrefix=auto, attackers can inject malicious HTML code to pages that have not been rendered and cached, yet. As a result, injected values would be cached and delivered to other website visitors (persisted cross-site scripting). Individual code which relies on the resolved value of GeneralUtility::getIndpEnv('SCRIPT_NAME') and corresponding usages (as shown below) are vulnerable as well. Additional investigations confirmed that at least Apache web server deployments using CGI (FPM, FCGI/FastCGI, and similar) are affected. However, there still might be the risk that other scenarios like nginx, IIS, or Apache/mod_php are vulnerable. The usage of server environment variable PATH_INFO has been removed from corresponding processings in GeneralUtility::getIndpEnv(). Besides that, the public property TypoScriptFrontendController::$absRefPrefix is encoded for both being used as a URI component and for being used as a prefix in an HTML context. This mitigates the cross-site scripting vulnerability. Users are advised to update to TYPO3 versions 8.7.51 ELTS, 9.5.40 ELTS, 10.4.35 LTS, 11.5.23 LTS and 12.2.0 which fix this problem. F…