CVE-2025-30537 identifies a stored Cross-site Scripting (XSS) vulnerability in the Cristian Sarov Upload Quota per User plugin, which is used to manage upload quotas on a per-user basis. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, allowing malicious scripts to be injected and stored persistently. When other users or administrators view the affected pages, the malicious payload executes in their browsers, potentially leading to session hijacking, credential theft, unauthorized actions, or malware distribution. This vulnerability affects all versions up to and including 1.3. No CVSS score has been assigned yet, and no patches or known exploits have been reported at the time of publication. The vulnerability is significant because stored XSS attacks can have widespread impact, especially in multi-user environments. Exploitation does not require user authentication or interaction beyond viewing the compromised page, increasing the attack surface. The plugin’s role in managing upload quotas suggests it is integrated into web applications that handle user-generated content, making it a critical vector for attack. Proper mitigation involves sanitizing and encoding all user inputs and outputs, deploying web application firewalls, and applying patches once available.

The impact of this vulnerability is substantial for organizations using the Cristian Sarov Upload Quota per User plugin. Stored XSS can lead to theft of user credentials, session tokens, and other sensitive information, enabling attackers to impersonate users or administrators. It can also facilitate the spread of malware or defacement of websites, damaging organizational reputation and trust. In environments where sensitive or regulated data is handled, this could lead to compliance violations and financial penalties. The vulnerability’s ease of exploitation without authentication increases risk, especially in public-facing web applications. Organizations with large user bases or those relying on this plugin for critical upload management are particularly vulnerable. Additionally, attackers could leverage this vulnerability as a foothold for further network intrusion or lateral movement. The absence of known exploits currently provides a window for proactive mitigation, but the risk remains high due to the nature of stored XSS.

To mitigate this vulnerability, organizations should first implement strict input validation and output encoding on all user-supplied data within the Upload Quota per User plugin. Employ context-aware encoding to neutralize scripts in HTML, JavaScript, and attribute contexts. Deploy Web Application Firewalls (WAFs) with rules designed to detect and block XSS payloads targeting this plugin. Monitor web application logs for unusual input patterns or error messages indicative of attempted exploitation. Restrict user privileges to minimize the impact of compromised accounts. Conduct regular security assessments and penetration testing focused on web application vulnerabilities. Stay informed about vendor updates and apply patches promptly once released. If immediate patching is not possible, consider temporarily disabling or restricting the plugin’s functionality to reduce exposure. Educate administrators and users about the risks of XSS and safe browsing practices. Finally, implement Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in browsers.