CVE-2026-25331 is a DOM-based Cross-site Scripting (XSS) vulnerability identified in the Melapress WP Activity Log plugin for WordPress, affecting all versions up to and including 5.5.4. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, which allows malicious actors to inject and execute arbitrary JavaScript code within the context of a victim's browser session. Unlike reflected or stored XSS, DOM-based XSS occurs entirely on the client side, manipulating the Document Object Model without server-side sanitization. This can be exploited by tricking authenticated users into visiting crafted URLs or interacting with malicious content, leading to session hijacking, theft of sensitive information, or unauthorized actions performed with the victim’s privileges. The plugin in question is widely used for logging and auditing WordPress activity, making it a critical component for security monitoring. Although no public exploits have been reported yet, the vulnerability's nature and the plugin's role in security auditing elevate the risk profile. The absence of a CVSS score indicates that the vulnerability is newly published and awaiting further analysis or patching. The vulnerability was reserved and published in early February 2026, with no patch links currently available, emphasizing the need for vigilance and proactive mitigation by administrators. The vulnerability affects WordPress sites using this plugin, which are common across many European organizations, especially those relying on WordPress for content management and security auditing.

For European organizations, exploitation of this DOM-based XSS vulnerability could lead to significant confidentiality and integrity breaches. Attackers could hijack user sessions, steal authentication tokens, or perform unauthorized actions within the context of the compromised user, potentially leading to data leakage or manipulation of audit logs. This is particularly critical for organizations that rely on WP Activity Log for security monitoring, as tampering with audit data could mask malicious activities or hinder incident response. The availability impact is generally low for XSS vulnerabilities, but the overall trustworthiness of the affected web applications could be severely undermined. Given the widespread use of WordPress and associated plugins in Europe, especially in sectors like government, finance, and healthcare, the risk of targeted attacks exploiting this vulnerability is considerable. The lack of known exploits currently provides a window for mitigation, but the ease of exploitation without authentication and no user interaction beyond visiting a malicious link increases the urgency for remediation.

1. Monitor the Melapress WP Activity Log plugin vendor announcements closely and apply any security patches immediately upon release. 2. Until a patch is available, consider temporarily disabling the plugin or restricting its use to trusted administrators only. 3. Implement strict input validation and output encoding on all user-controllable inputs within the WordPress environment, especially those handled by the plugin. 4. Deploy Content Security Policy (CSP) headers to restrict the execution of inline scripts and reduce the impact of potential XSS attacks. 5. Educate users and administrators about the risks of clicking on untrusted links and encourage the use of security-aware browsing practices. 6. Regularly audit and monitor WordPress logs for unusual activity that might indicate exploitation attempts or successful compromise. 7. Employ web application firewalls (WAFs) with rules tailored to detect and block XSS payloads targeting WordPress plugins. 8. Conduct internal security assessments focusing on client-side vulnerabilities to identify and remediate similar issues proactively.