CVE-2022-31049 is a cross-site scripting (XSS) vulnerability identified in TYPO3, an open-source web content management system widely used for building and managing websites. The vulnerability arises from improper neutralization of user-supplied input during the generation of HTML emails sent by TYPO3. Specifically, in TYPO3 versions prior to 9.5.34 ELTS, 10.4.29, and 11.5.11, user-submitted content was not properly encoded before being embedded in HTML email messages. This flaw allows an attacker to inject malicious scripts into the HTML content of emails generated by TYPO3. When these emails are viewed in vulnerable mail clients that render HTML content, the malicious scripts can execute in the context of the email client, potentially leading to unauthorized actions such as session hijacking, credential theft, or further malware delivery. The vulnerability affects TYPO3 versions 9.0.0 up to but not including 9.5.34, 10.0.0 up to but not including 10.4.29, and 11.0.0 up to but not including 11.5.11. TYPO3 has addressed this issue by properly encoding user input in the affected versions mentioned. Notably, exploitation requires that the attacker can submit content that will be included in emails sent by TYPO3 and that the recipient uses a mail client vulnerable to script execution in HTML emails. There are no known exploits in the wild at the time of this analysis, and the vulnerability is classified under CWE-79, which pertains to improper neutralization of input leading to cross-site scripting.

For European organizations using TYPO3 within the affected version ranges, this vulnerability could lead to significant security risks. The primary impact is on the confidentiality and integrity of user data, as malicious scripts executed within email clients could steal sensitive information such as authentication tokens, personal data, or corporate credentials. Additionally, attackers could leverage this vulnerability to perform phishing attacks or distribute malware, potentially compromising organizational networks. The availability impact is limited but could manifest if attackers use the vulnerability to disrupt email communications or trigger denial-of-service conditions via malicious payloads. Given TYPO3's popularity among European public sector entities, educational institutions, and SMEs, exploitation could undermine trust in digital communications and lead to reputational damage. However, the requirement for user interaction (opening the malicious email) and the dependency on vulnerable mail clients somewhat limit the scope and ease of exploitation. Nonetheless, organizations with high email traffic and automated content submission to TYPO3 systems are at increased risk.

Organizations should prioritize upgrading TYPO3 installations to versions 9.5.34 ELTS, 10.4.29, or 11.5.11 or later, where the vulnerability has been fixed. Beyond patching, administrators should implement strict input validation and sanitization on all user-submitted content, especially content that will be included in emails. Configuring email clients to disable automatic HTML rendering or to use plain-text email viewing can reduce the risk of script execution. Employing email security gateways that scan and sanitize incoming and outgoing emails for malicious scripts is recommended. Additionally, organizations should educate users about the risks of opening unexpected or suspicious emails, particularly those containing HTML content. Monitoring email logs for unusual patterns or unexpected content generation can help detect exploitation attempts. Finally, implementing Content Security Policy (CSP) headers where applicable and ensuring that mail clients are updated to versions that mitigate script execution risks can further reduce exposure.