CVE-2025-63520 Overview
CVE-2025-63520 is a Cross-Site Scripting (XSS) vulnerability identified in FeehiCMS version 2.1.1. The vulnerability exists in the id parameter of the User Update function, accessible via the ?r=user%2Fupdate route. This reflected XSS flaw allows attackers to inject malicious scripts that execute in the context of a victim's browser session when they interact with a crafted URL.
Cross-Site Scripting vulnerabilities remain one of the most prevalent web application security issues, enabling attackers to steal session tokens, hijack user accounts, deface websites, or redirect users to malicious sites. With a CVSS score of 6.1 (Medium severity), this vulnerability poses a significant risk to organizations running unpatched FeehiCMS installations.
Critical Impact
Attackers can execute arbitrary JavaScript in authenticated user sessions, potentially leading to session hijacking, credential theft, and unauthorized administrative actions within the FeehiCMS platform.
Affected Products
- FeehiCMS version 2.1.1
- Feehi FeehiCMS content management system
Discovery Timeline
- 2025-12-01 - CVE-2025-63520 published to NVD
- 2025-12-02 - Last updated in NVD database
Technical Details for CVE-2025-63520
Vulnerability Analysis
The vulnerability resides in the User Update functionality of FeehiCMS 2.1.1. The id parameter passed to the ?r=user%2Fupdate endpoint fails to properly sanitize user-supplied input before reflecting it back in the HTTP response. This lack of input validation allows attackers to inject arbitrary HTML and JavaScript code that executes in the victim's browser.
The CVSS v3.1 vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N indicates:
- Attack Vector (AV:N): Network-based exploitation
- Attack Complexity (AC:L): Low complexity required
- Privileges Required (PR:N): No authentication needed
- User Interaction (UI:R): Requires victim to click a malicious link
- Scope (S:C): Changed scope, impacting resources beyond the vulnerable component
- Confidentiality/Integrity Impact (C:L/I:L): Low impact on both
- Availability Impact (A:N): No availability impact
The EPSS (Exploit Prediction Scoring System) score of 0.029% with a percentile of 7.466 suggests a relatively low probability of active exploitation in the wild, though this does not diminish the need for remediation.
Root Cause
The root cause of this vulnerability is improper input validation and output encoding in the User Update function. The application fails to sanitize the id parameter before including it in the rendered HTML response. This is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), a common weakness in web applications that trust user input without proper validation.
Attack Vector
The attack leverages the network-accessible User Update endpoint. An attacker crafts a malicious URL containing JavaScript payload in the id parameter. When an authenticated administrator or user clicks this link, the malicious script executes within their browser session. The changed scope (S:C) indicates the vulnerability in FeehiCMS can impact the user's browser context beyond the application itself.
The exploitation scenario typically involves social engineering to convince a target user to click on the malicious link, which could be delivered via phishing emails, forum posts, or other communication channels. Technical details and proof-of-concept information are available in the vendor advisory and CVE documentation.
Detection Methods for CVE-2025-63520
Indicators of Compromise
- Unusual URL patterns containing encoded script tags in the id parameter of User Update requests
- HTTP requests to ?r=user%2Fupdate with suspicious id parameter values containing HTML entities or JavaScript
- Web application firewall (WAF) alerts for XSS patterns targeting the FeehiCMS user management endpoints
- Browser console errors or unexpected script execution on FeehiCMS administrative pages
Detection Strategies
Organizations should implement the following detection strategies:
Web Application Firewall Rules: Configure WAF rules to detect and block common XSS payloads in the id parameter of requests to the user/update endpoint.
Log Analysis: Monitor web server access logs for requests containing suspicious characters such as <script>, javascript:, onerror, or other common XSS vectors in query parameters.
Endpoint Detection: Deploy endpoint protection solutions capable of detecting browser-based attacks and unauthorized script execution.
Content Security Policy Monitoring: Implement and monitor CSP violation reports to detect attempted XSS attacks.
Monitoring Recommendations
Security teams should enable verbose logging for the FeehiCMS application, particularly for the user management module. Establish baseline traffic patterns and alert on anomalous requests to the ?r=user%2Fupdate endpoint. Integration with SIEM solutions will provide centralized visibility into potential exploitation attempts across the environment.
How to Mitigate CVE-2025-63520
Immediate Actions Required
- Review the vendor advisory at https://github.com/liufee/cms/issues/74 for official guidance and patches
- Implement input validation and output encoding for the id parameter in the User Update function
- Deploy Web Application Firewall (WAF) rules to filter XSS payloads targeting the vulnerable endpoint
- Restrict administrative access to FeehiCMS to trusted networks using IP allowlisting
- Implement Content Security Policy (CSP) headers to mitigate the impact of successful XSS attacks
Patch Information
Organizations should monitor the official FeehiCMS GitHub repository at https://github.com/liufee/cms for security patches addressing this vulnerability. The issue has been reported to the vendor via GitHub Issues. Until a patch is released, implementing the workarounds below is strongly recommended.
Workarounds
If immediate patching is not possible, the following workarounds can help mitigate the risk:
Input Sanitization: Manually implement server-side input validation to reject or sanitize potentially malicious characters in the id parameter before processing.
Content Security Policy: Implement strict CSP headers to prevent inline script execution:
Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'
Network Segmentation: Restrict access to the FeehiCMS administrative interface to internal networks only, reducing the attack surface for social engineering attempts.
User Awareness: Educate administrative users about the risks of clicking untrusted links while authenticated to the CMS platform.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
