CVE-2025-5236 is a stored Cross-Site Scripting (XSS) vulnerability identified in the NinjaTeam Chat for Telegram plugin for WordPress. This vulnerability affects all versions up to and including version 1.1 of the plugin. The root cause is insufficient input sanitization and output escaping of the 'username' parameter, which allows authenticated users with Contributor-level access or higher to inject arbitrary malicious scripts into pages generated by the plugin. When other users access these pages, the injected scripts execute in their browsers, potentially leading to session hijacking, defacement, or unauthorized actions performed on behalf of the victim. The vulnerability has a CVSS 3.1 base score of 6.4, indicating a medium severity level. The vector metrics indicate that the attack can be performed remotely over the network (AV:N), with low attack complexity (AC:L), requiring privileges (PR:L) but no user interaction (UI:N). The scope is changed (S:C), meaning the vulnerability affects resources beyond the security scope of the vulnerable component. The impact affects confidentiality and integrity at a low level but does not affect availability. No known exploits are currently reported in the wild, and no patches have been published yet. The vulnerability was publicly disclosed on May 30, 2025. Stored XSS vulnerabilities in WordPress plugins are particularly dangerous because they can affect multiple users and administrators, potentially compromising entire websites or networks if exploited. Given that the vulnerability requires authenticated access at Contributor level or above, attackers need to have some level of access, but this is often achievable through social engineering or exploiting other vulnerabilities. The NinjaTeam Chat for Telegram plugin is used to integrate Telegram chat functionality into WordPress sites, which may be popular among organizations using Telegram for communication and customer engagement.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of their WordPress-based websites that utilize the NinjaTeam Chat for Telegram plugin. Exploitation could lead to unauthorized script execution, enabling attackers to steal session cookies, perform actions on behalf of legitimate users, or deliver further malware payloads. This could result in data breaches, defacement of public-facing websites, or unauthorized access to internal communication channels integrated via Telegram. The impact is heightened for organizations that rely heavily on WordPress for customer interaction or internal communication, including SMEs, media companies, and public sector entities. Additionally, GDPR compliance could be jeopardized if personal data is exposed or manipulated due to this vulnerability, leading to potential regulatory fines and reputational damage. The requirement for authenticated access somewhat limits the attack surface but does not eliminate risk, as attackers may gain contributor-level access through phishing or other means. The absence of known exploits in the wild currently reduces immediate risk but does not preclude future exploitation. Organizations with high web traffic or sensitive data hosted on vulnerable WordPress sites are at greater risk of targeted attacks leveraging this vulnerability.

1. Immediate mitigation should focus on restricting Contributor-level access to trusted users only, implementing strict user account management and monitoring for suspicious activity. 2. Employ Web Application Firewalls (WAFs) with custom rules to detect and block malicious payloads targeting the 'username' parameter in the NinjaTeam Chat for Telegram plugin. 3. Conduct a thorough audit of all user-generated content within the plugin to identify and remove any suspicious or injected scripts. 4. Until an official patch is released, consider disabling or uninstalling the NinjaTeam Chat for Telegram plugin if feasible, especially on high-risk or sensitive sites. 5. Implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers, mitigating the impact of any successful XSS injection. 6. Monitor security advisories from the vendor and WordPress community for patch releases and apply updates promptly once available. 7. Educate users with Contributor-level access about phishing and social engineering risks to prevent privilege escalation. 8. Regularly back up website data and configurations to enable rapid recovery in case of compromise. These measures go beyond generic advice by focusing on access control, proactive detection, and layered defenses tailored to the specifics of this vulnerability and the WordPress environment.