CVE-2025-6590 is a vulnerability categorized under CWE-200, indicating exposure of sensitive information to unauthorized actors within the MediaWiki software developed by the Wikimedia Foundation. The issue resides specifically in the program file includes/htmlform/fields/HTMLUserTextField.php, which handles user text input fields in HTML forms. This vulnerability affects all versions of MediaWiki up to 1.39.12 and versions 1.42.76 through 1.44.0, implying a broad range of installations are impacted. The vulnerability allows an attacker to gain access to sensitive information that should otherwise be protected, potentially through crafted requests that exploit improper handling or validation of user input fields. According to the CVSS v4.0 vector, the attack vector is network-based (AV:N), with high attack complexity (AC:H), requiring partial user interaction (UI:A), no privileges (PR:N), and no authentication (AT:P). The impact is limited to confidentiality (VC:L), with no impact on integrity or availability. The scope is high (SC:H), indicating that the vulnerability affects components beyond the vulnerable code itself, possibly impacting other parts of the system. No known exploits are currently reported in the wild, and no patches are linked yet, suggesting that remediation may require monitoring official Wikimedia Foundation updates. The vulnerability's presence in a widely used wiki platform makes it a concern for organizations relying on MediaWiki for internal or public knowledge management.

For European organizations, the exposure of sensitive information through this vulnerability could lead to unauthorized disclosure of internal documentation, user data, or other confidential content stored in MediaWiki instances. This could facilitate further attacks such as social engineering, phishing, or targeted espionage, especially for organizations that use MediaWiki for critical knowledge bases or collaborative projects. The confidentiality breach could damage organizational reputation, violate data protection regulations such as GDPR, and potentially result in legal and financial consequences. Since MediaWiki is often used by public institutions, educational entities, and enterprises across Europe, the impact could be widespread. However, the medium severity and the requirement for partial user interaction and high attack complexity somewhat limit the immediacy of risk. Nonetheless, organizations with publicly accessible MediaWiki installations or those with sensitive content should consider this vulnerability a significant concern.

1. Monitor official Wikimedia Foundation channels for patches or updates addressing CVE-2025-6590 and apply them promptly once available. 2. Until patches are released, restrict access to MediaWiki installations to trusted networks and authenticated users to reduce exposure. 3. Review and harden form input handling configurations, especially those related to HTMLUserTextField.php, to ensure no sensitive data is inadvertently exposed. 4. Implement web application firewalls (WAFs) with rules designed to detect and block suspicious requests targeting form input fields. 5. Conduct thorough audits of MediaWiki content and permissions to minimize sensitive information exposure. 6. Educate users about the risks of interacting with untrusted links or content that could trigger the vulnerability. 7. Consider deploying network segmentation and monitoring to detect anomalous access patterns to MediaWiki services. 8. Regularly back up MediaWiki data and configurations to enable recovery in case of exploitation.