CVE-2025-52133 is a medium-severity cross-site scripting (XSS) vulnerability identified in the Mocca Calendar application, a component of the xwiki-contrib project. This vulnerability affects versions prior to 2.15 of the Mocca Calendar. The issue arises due to improper neutralization of input during web page generation, specifically when importing calendar data. An attacker can exploit this vulnerability by injecting malicious scripts into the 'title' field of a calendar import. Because the application fails to properly sanitize or encode this input, the malicious script can be executed in the context of the victim's browser when viewing the calendar. The CVSS 3.1 base score is 6.4, indicating a medium severity level. The vector string (AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N) reveals that the attack can be performed remotely over the network with low attack complexity, requires low privileges (authenticated user), and no user interaction. The scope is changed, meaning the vulnerability affects components beyond the initially vulnerable component. The impact affects confidentiality and integrity to a limited extent but does not affect availability. No known exploits are currently in the wild, and no official patches have been linked yet. XSS vulnerabilities like this can be leveraged to steal session cookies, perform actions on behalf of authenticated users, or deliver further malicious payloads, potentially leading to account compromise or data leakage within the affected XWiki environment.

For European organizations using XWiki with the Mocca Calendar extension, this vulnerability poses a risk of unauthorized script execution within their internal collaboration platforms. Since XWiki is often used for knowledge management and collaboration, exploitation could lead to theft of session tokens, unauthorized data access, or manipulation of calendar events. This could disrupt business workflows and lead to leakage of sensitive organizational information. The requirement for low privileges means that any authenticated user, including potentially compromised or malicious insiders, could exploit this vulnerability. Given the collaborative nature of XWiki, the impact could extend to multiple departments or teams. Additionally, the cross-site scripting could be used as a foothold for further attacks within the corporate network. European organizations with strict data protection regulations (e.g., GDPR) may face compliance risks if such vulnerabilities lead to data breaches. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as the vulnerability is publicly disclosed.

To mitigate this vulnerability, European organizations should: 1) Upgrade the Mocca Calendar extension to version 2.15 or later as soon as it becomes available, since this version addresses the vulnerability. 2) Until an official patch is released, implement input validation and output encoding on the 'title' field during calendar imports at the application or proxy level to neutralize potentially malicious scripts. 3) Restrict calendar import functionality to trusted users only, minimizing the risk of malicious input. 4) Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts within the XWiki environment. 5) Conduct regular security audits and penetration testing focused on XWiki extensions to detect similar issues proactively. 6) Educate users about the risks of importing calendar data from untrusted sources. 7) Monitor logs for unusual activity related to calendar imports or script execution attempts. These steps go beyond generic advice by focusing on immediate containment, user access control, and layered defense strategies specific to the XWiki Mocca Calendar context.