CVE-2022-43692 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. Concrete CMS, formerly known as concrete5, is an open-source content management system widely used for building and managing websites. The vulnerability arises when an attacker crafts a malicious URL that, if visited by an administrator using an outdated web browser lacking modern XSS protection mechanisms, can trigger the execution of arbitrary JavaScript code within the administrator's browser context. This reflected XSS occurs because user-supplied input is not properly sanitized or encoded before being reflected in the web application's response. The vulnerability requires no prior authentication (PR:N) but does require user interaction (UI:R), specifically that the targeted administrator clicks or visits the malicious URL. The attack vector is network-based (AV:N), meaning it can be exploited remotely over the internet. The vulnerability impacts confidentiality and integrity by allowing an attacker to potentially steal session cookies, perform actions on behalf of the administrator, or manipulate displayed content, but does not affect availability. The scope is changed (S:C), indicating that the vulnerability can affect resources beyond the initially vulnerable component, such as other parts of the CMS or administrative functions. The CVSS v3.1 base score is 6.1, categorized as medium severity. The vulnerability is remediated by upgrading Concrete CMS to versions 8.5.10 or later in the 8.x branch, or 9.1.3 or later in the 9.x branch. No known exploits in the wild have been reported to date. The vulnerability is classified under CWE-79, which corresponds to improper neutralization of input leading to XSS attacks. The risk is heightened if administrators use outdated browsers without built-in XSS filters or protections, which modern browsers typically provide by default.

For European organizations using Concrete CMS, this vulnerability poses a moderate risk primarily to the confidentiality and integrity of administrative sessions. Successful exploitation could allow attackers to hijack administrator sessions, leading to unauthorized content changes, privilege escalation, or deployment of malicious content to site visitors. This could damage organizational reputation, lead to data leakage, or facilitate further attacks such as phishing or malware distribution. Since the vulnerability requires the administrator to interact with a malicious URL, social engineering or phishing campaigns could be used to trigger exploitation. The impact is particularly significant for organizations with high-value web assets managed via Concrete CMS, such as government portals, educational institutions, or e-commerce platforms. The lack of availability impact means service disruption is unlikely, but the potential for stealthy compromise remains. Given that many European organizations enforce browser update policies, the risk may be mitigated if administrators use modern browsers with XSS protections enabled. However, legacy systems or environments with outdated browsers remain vulnerable. The reflected XSS could also be leveraged as part of multi-stage attacks targeting European organizations, especially those with strategic or sensitive web infrastructure.

Upgrade all Concrete CMS installations to version 8.5.10 or later in the 8.x branch, or 9.1.3 or later in the 9.x branch to apply the official patch addressing this vulnerability. Enforce strict browser update policies for all administrators managing Concrete CMS, ensuring use of modern browsers with built-in XSS protection (e.g., latest versions of Chrome, Firefox, Edge). Implement Content Security Policy (CSP) headers to restrict the execution of untrusted scripts and reduce the impact of reflected XSS attacks. Educate administrators about phishing and social engineering risks, emphasizing caution when clicking on URLs, especially those received via email or messaging platforms. Use web application firewalls (WAFs) with rulesets tuned to detect and block reflected XSS payloads targeting Concrete CMS endpoints. Regularly audit and sanitize all user inputs and URL parameters within the CMS environment to prevent injection of malicious scripts. Monitor web server and application logs for unusual URL requests or repeated attempts to exploit XSS vulnerabilities. Consider isolating administrative interfaces behind VPNs or IP whitelisting to reduce exposure to external attackers.