CVE-2025-62657 is a Stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting the MediaWiki PageForms extension version 1.44. This extension is widely used to create and manage forms within MediaWiki installations, enabling structured data entry. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, allowing malicious scripts to be stored and later executed in the context of users viewing the affected pages. The attack vector is network-based (AV:N), but requires high attack complexity (AC:H), no privileges required for the attack itself (PR:H indicates high privileges needed, but CVSS vector is somewhat ambiguous here), and user interaction (UI:P). The vulnerability impacts the confidentiality and integrity of user data (VC:H, VI:L), but does not affect availability or authentication mechanisms. Exploitation requires an attacker with high privileges to inject malicious content and a victim user to interact with the crafted page, which limits the attack surface. No known exploits have been reported in the wild, and no patches are currently linked, indicating a need for proactive mitigation. The vulnerability was published on October 20, 2025, shortly after being reserved on October 17, 2025, suggesting recent discovery. The Wikimedia Foundation is the vendor responsible for the extension. Stored XSS can lead to session hijacking, defacement, or redirection to malicious sites, posing risks especially in collaborative environments where multiple users interact with content.

For European organizations, this vulnerability poses a moderate risk primarily to confidentiality and integrity of data within MediaWiki installations using the PageForms extension. Organizations in government, academia, and public information sectors frequently use MediaWiki for collaborative knowledge management, making them potential targets. Successful exploitation could allow attackers to execute arbitrary scripts in the context of users with access to the affected wiki pages, potentially leading to session hijacking, unauthorized actions, or data leakage. The requirement for high privileges to inject malicious content limits the threat to insiders or compromised accounts, but the widespread use of MediaWiki in Europe increases exposure. Disruption of trusted information sources or defacement could undermine public trust and operational continuity. The vulnerability does not directly impact availability but could facilitate further attacks that do. Given the collaborative nature of MediaWiki, the scope of affected systems can be broad within an organization, amplifying potential damage.

European organizations should immediately audit their MediaWiki installations to identify use of the PageForms extension version 1.44. Until an official patch is released, restrict high privilege accounts to trusted personnel only and enforce strong authentication and monitoring to prevent account compromise. Implement strict input validation and output encoding on all user-supplied data within PageForms forms and templates to neutralize malicious scripts. Employ Content Security Policy (CSP) headers to limit script execution sources and reduce impact of XSS. Regularly review and sanitize existing wiki content to detect and remove any injected scripts. Monitor logs for unusual activities indicative of exploitation attempts. Educate users about the risks of interacting with untrusted wiki content. Coordinate with Wikimedia Foundation for timely updates and patches. Consider isolating MediaWiki instances or limiting external access where feasible to reduce exposure.