CVE-2025-24289 is a high-severity vulnerability affecting the UCRM Client Signup Plugin developed by Ubiquiti Inc, specifically versions 1.3.5 and earlier. The vulnerability chain begins with a Cross-Site Request Forgery (CSRF) attack that leads to a Cross-Site Scripting (XSS) condition. An attacker can exploit this by tricking an administrator into visiting a crafted malicious webpage. Because the plugin is designed to handle client signup processes, the vulnerability allows an attacker to escalate privileges by executing arbitrary scripts in the context of the administrator's session. This can compromise confidentiality, integrity, and availability of the affected system. The plugin is disabled by default, which reduces the attack surface but does not eliminate risk if enabled. The CVSS 3.0 base score is 7.5, indicating a high severity, with the vector string showing network attack vector (AV:N), high attack complexity (AC:H), no privileges required (PR:N), user interaction required (UI:R), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). No known exploits are currently reported in the wild, but the vulnerability’s nature and impact make it a significant threat if exploited.

For European organizations, the impact of this vulnerability can be substantial, especially for those using Ubiquiti's UCRM platform to manage client signups and billing. Successful exploitation could lead to unauthorized administrative access, allowing attackers to manipulate client data, disrupt service availability, or pivot to other internal systems. This could result in data breaches involving sensitive customer information, financial loss, reputational damage, and regulatory non-compliance under GDPR. Since the attack requires an administrator to visit a malicious page, phishing campaigns targeting IT staff or administrators could be an effective vector. The fact that the plugin is disabled by default reduces widespread risk but organizations that have enabled it without applying patches remain vulnerable. The high confidentiality, integrity, and availability impacts mean critical business operations could be disrupted, affecting service providers and their customers across Europe.

1. Immediately verify if the UCRM Client Signup Plugin is enabled in your environment. If it is not required, disable it to eliminate the attack surface. 2. Apply any available patches or updates from Ubiquiti as soon as they are released; monitor vendor communications closely since no patch links are currently provided. 3. Implement strict administrative browsing policies to restrict administrators from visiting untrusted or external websites, reducing the risk of CSRF/XSS exploitation via malicious pages. 4. Employ Content Security Policy (CSP) headers and other web application security controls to mitigate the impact of XSS attacks. 5. Conduct targeted phishing awareness training for administrators and IT staff to recognize and avoid malicious links or pages. 6. Monitor logs for unusual administrative activity or signs of exploitation attempts. 7. Consider network segmentation and access controls to limit the exposure of UCRM administrative interfaces to trusted networks only. 8. Regularly audit plugin usage and configurations to ensure compliance with security best practices.