CVE-2025-62871 identifies a Cross-Site Request Forgery (CSRF) vulnerability in the Just TinyMCE Custom Styles plugin, versions up to and including 1.2.1, developed by Alex Prokopenko / JustCoded. This plugin extends the TinyMCE editor by allowing custom styles to be applied within content management systems. The vulnerability arises because the plugin does not adequately verify the origin of requests that modify its settings or styles, enabling attackers to craft malicious web pages that, when visited by an authenticated user, cause the user's browser to send unauthorized requests to the vulnerable plugin. The attack vector is network-based (remote), requires no privileges (PR:N), but does require user interaction (UI:R), such as visiting a malicious website. The impact is limited to integrity (I:L), meaning attackers can alter plugin configurations or styles but cannot access confidential data or disrupt availability. The vulnerability scope is unchanged (S:U), affecting only the vulnerable component. The CVSS 3.1 base score is 4.3, reflecting a medium severity level. No known exploits have been reported in the wild, and no official patches have been linked yet. The vulnerability was reserved on 2025-10-24 and published on 2025-12-09. The absence of CWE identifiers suggests a straightforward CSRF issue without complex underlying coding errors. This vulnerability is significant for websites relying on this plugin for content styling, as unauthorized style changes could be used for defacement, phishing, or to facilitate further attacks.

For European organizations, the primary impact of CVE-2025-62871 lies in the potential unauthorized modification of website appearance or behavior via the Just TinyMCE Custom Styles plugin. While this does not directly compromise sensitive data or cause service outages, it can undermine the integrity of web content, damage brand reputation, and erode user trust. Attackers could exploit this to inject misleading styles or visual elements that facilitate phishing or social engineering attacks targeting site visitors. Organizations in sectors with high public-facing web presence, such as e-commerce, media, and government, may face reputational harm or regulatory scrutiny if manipulated content leads to user harm. Additionally, altered styles could be used as a stepping stone for more sophisticated attacks if combined with other vulnerabilities. The medium severity rating indicates that while the risk is not critical, it should not be ignored, especially in environments where the plugin is widely deployed.

To mitigate CVE-2025-62871, organizations should first verify if they use the Just TinyMCE Custom Styles plugin version 1.2.1 or earlier. Until an official patch is released, administrators should implement the following measures: 1) Enforce strict anti-CSRF protections by ensuring that all state-changing requests include validated CSRF tokens and that the server verifies these tokens correctly. 2) Configure web application firewalls (WAFs) to detect and block suspicious cross-site requests targeting the plugin endpoints. 3) Restrict plugin management interfaces to trusted IP ranges or VPN access where feasible. 4) Educate users and administrators about the risks of clicking unknown links or visiting untrusted websites while authenticated. 5) Monitor web server and application logs for unusual POST requests or changes to plugin configurations. 6) Once available, promptly apply official patches or updates from the vendor. 7) Consider temporarily disabling the plugin if it is not critical to operations or replacing it with alternative solutions that follow secure coding practices.