CVE-2022-43967 is a reflected Cross-Site Scripting (XSS) vulnerability affecting Concrete CMS versions below 8.5.10 and between 9.0.0 and 9.1.2. The vulnerability arises from un-sanitized output in the multilingual report feature, which allows an attacker to inject malicious scripts that are reflected back to the user. This type of vulnerability can be exploited by tricking a user into clicking a specially crafted URL or interacting with a manipulated web page, causing the victim's browser to execute attacker-controlled JavaScript code. The CVSS 3.1 base score of 6.1 indicates a medium severity level, with an attack vector of network (remote exploitation), low attack complexity, no privileges required, but requiring user interaction. The impact affects confidentiality and integrity but does not affect availability. The vulnerability scope is changed (S:C), meaning the vulnerability can affect resources beyond the vulnerable component. Concrete CMS is a popular open-source content management system used for building and managing websites. The reflected XSS vulnerability could be leveraged to steal session cookies, perform actions on behalf of authenticated users, or redirect users to malicious sites. The recommended remediation is to update Concrete CMS to version 9.1.3 or later, or 8.5.10 or later, where the issue has been fixed by properly sanitizing output in the multilingual report. No known exploits in the wild have been reported to date, but the vulnerability is publicly disclosed and could be targeted by attackers seeking to compromise websites running vulnerable versions of Concrete CMS.

For European organizations using Concrete CMS, this vulnerability poses a risk primarily to the confidentiality and integrity of user sessions and data. Attackers exploiting the reflected XSS could hijack user sessions, leading to unauthorized access to sensitive information or administrative functions. This is particularly concerning for organizations managing personal data under GDPR, as exploitation could lead to data breaches and regulatory penalties. The vulnerability could also be used to deface websites or distribute malware via malicious redirects, damaging organizational reputation. Since Concrete CMS is used by a variety of sectors including government, education, and small to medium enterprises, the impact could be widespread. The requirement for user interaction (clicking a malicious link) means social engineering could be used to increase attack success. However, the lack of known active exploits reduces immediate risk but does not eliminate it. Organizations hosting multilingual websites are especially at risk due to the vulnerability residing in the multilingual report feature. Overall, the threat could disrupt trust in web services and lead to compliance issues if exploited.

European organizations should prioritize upgrading Concrete CMS installations to version 9.1.3 or 8.5.10 and above to remediate this vulnerability. Beyond patching, organizations should implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts, reducing the impact of potential XSS attacks. Web Application Firewalls (WAFs) can be configured to detect and block reflected XSS payloads targeting the multilingual report endpoints. Regular security audits and code reviews of custom CMS plugins or themes should be conducted to ensure no additional XSS vectors exist. User awareness training should emphasize caution with unsolicited links, especially those that appear to interact with site reports or administrative functions. Logging and monitoring for unusual URL parameters or error messages related to the multilingual report can help detect attempted exploitation. Finally, organizations should maintain an inventory of CMS versions in use to ensure timely patch management and vulnerability tracking.