CVE-2025-5939 is a Stored Cross-Site Scripting (XSS) vulnerability identified in the Telegram for WP plugin for WordPress, developed by amir-mousavi. This vulnerability affects all versions up to and including 1.6.1. The root cause is improper neutralization of input during web page generation, specifically insufficient input sanitization and output escaping in the plugin's admin settings. The vulnerability manifests in multi-site WordPress installations or installations where the 'unfiltered_html' capability is disabled. An attacker with administrator-level permissions or higher can inject arbitrary JavaScript code into the admin settings pages. This malicious script will execute whenever any user accesses the compromised page, potentially leading to session hijacking, privilege escalation, or other client-side attacks. The vulnerability requires high privileges (administrator or above) to exploit, no user interaction is needed once the script is injected, and the attack surface is limited to multi-site or restricted HTML environments. The CVSS v3.1 base score is 4.4 (medium severity), reflecting the network attack vector, high attack complexity, required privileges, no user interaction, and partial impact on confidentiality and integrity but no impact on availability. There are no known exploits in the wild and no patches currently available as of the publication date (June 13, 2025).

For European organizations using WordPress multi-site installations with the Telegram for WP plugin, this vulnerability poses a moderate risk. Since exploitation requires administrator-level access, the primary threat is from insider attackers or attackers who have already compromised admin credentials. Successful exploitation can lead to injection of malicious scripts that execute in the context of other administrators or users with access to the affected pages, potentially enabling theft of session tokens, unauthorized actions, or spreading malware within the organization’s web environment. This can undermine the confidentiality and integrity of administrative operations and user data. Given the plugin’s niche use case (integrating Telegram with WordPress), the impact is more pronounced in organizations relying heavily on this integration for communication or customer engagement. The vulnerability does not affect availability directly but could facilitate further attacks that degrade service. European organizations with strict data protection regulations (e.g., GDPR) may face compliance risks if user data is compromised through this vulnerability.

Restrict administrator access strictly to trusted personnel and enforce strong authentication mechanisms (e.g., multi-factor authentication) to reduce the risk of credential compromise. Audit and monitor multi-site WordPress installations for unusual administrative activity or unauthorized changes in plugin settings. Temporarily disable or remove the Telegram for WP plugin in multi-site environments until a security patch is released. If disabling the plugin is not feasible, limit the use of multi-site installations or enable 'unfiltered_html' capability cautiously, understanding the security trade-offs. Implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in the WordPress admin interface. Regularly update WordPress core and plugins, and subscribe to vendor or security mailing lists for timely patch releases. Conduct periodic security reviews and penetration testing focusing on WordPress plugins and multi-site configurations.