CVE-2026-31353: Feehi CMS Stored XSS Vulnerability

CVE-2026-31353 Overview

An authenticated stored cross-site scripting (XSS) vulnerability has been identified in Feehi CMS v2.1.1. The vulnerability exists within the Category module, where attackers with authenticated access can inject malicious web scripts or HTML through the Name parameter. Once stored, these scripts execute in the browsers of users who view the affected category, potentially leading to session hijacking, credential theft, or malicious redirects.

Critical Impact

Authenticated attackers can persistently inject malicious scripts into the Category module, enabling attacks against administrators and other users who view the compromised content.

Affected Products

• Feehi CMS version 2.1.1

Discovery Timeline

• 2026-04-06 - CVE CVE-2026-31353 published to NVD
• 2026-04-09 - Last updated in NVD database

Technical Details for CVE-2026-31353

Vulnerability Analysis

This stored XSS vulnerability occurs due to insufficient input sanitization in the Category module of Feehi CMS. When an authenticated user creates or modifies a category, the application fails to properly validate and sanitize the Name parameter before storing it in the database. Subsequently, when this category name is rendered in the user interface, the malicious payload executes in the context of the victim's browser session.

The attack requires low privileges (authenticated access) and user interaction (a victim must view the page containing the malicious category). However, because the payload is stored persistently, it can affect multiple users over time, including administrators with elevated privileges.

Root Cause

The vulnerability stems from improper input validation (CWE-79) in the Category module's form handling. The application does not adequately encode or sanitize user-supplied input in the Name parameter before storing it in the database or rendering it back to users. This allows HTML and JavaScript code to be interpreted by the browser rather than displayed as plain text.

Attack Vector

The attack is network-based and requires an authenticated session with permissions to access the Category module. An attacker crafts a malicious payload containing JavaScript code and submits it through the Name parameter when creating or editing a category. The payload is stored in the application's database and executes whenever a user (including administrators) views the category listing or details page.

The exploitation flow typically involves:

1. Attacker authenticates to the Feehi CMS administrative interface
2. Attacker navigates to the Category module
3. Attacker injects a crafted XSS payload into the Name field (e.g., <script> tags or event handlers)
4. The payload is stored without proper sanitization
5. When other users view the category, the malicious script executes in their browser context

For technical details and proof-of-concept information, see the GitHub Issue Discussion #84.

Detection Methods for CVE-2026-31353

Indicators of Compromise

• Presence of JavaScript code or HTML tags in category names within the database
• Unusual <script>, <img onerror=, or similar HTML event handlers stored in the name field of category records
• Reports of unexpected browser behavior or redirects when viewing category pages
• Session tokens or cookies being transmitted to external domains

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect XSS payloads in form submissions to the Category module
• Monitor database entries in the category table for suspicious HTML/JavaScript content patterns
• Review web server logs for unusual POST requests to category creation/update endpoints containing encoded script tags
• Deploy content security policy (CSP) headers to detect and report inline script execution attempts

Monitoring Recommendations

• Enable detailed logging for all administrative actions in Feehi CMS
• Configure alerting for database modifications to category tables containing potential XSS patterns
• Monitor for CSP violation reports that may indicate XSS exploitation attempts
• Review user session activity for signs of unauthorized access following category page views

How to Mitigate CVE-2026-31353

Immediate Actions Required

• Upgrade Feehi CMS to a patched version when available from the vendor
• Implement input validation and output encoding for all user-supplied data in the Category module
• Review and sanitize existing category entries in the database to remove any malicious payloads
• Restrict access to the Category module to only trusted administrators until patched

Patch Information

No official patch information is currently available. Monitor the Feehi CMS GitHub Repository for security updates and new releases. Track the GitHub Issue Discussion #84 for ongoing discussions regarding this vulnerability.

Workarounds

• Implement server-side input sanitization using HTML encoding libraries before storing category names
• Deploy Content Security Policy (CSP) headers with strict script-src directives to mitigate script execution
• Use a Web Application Firewall to filter malicious payloads in HTTP requests
• Limit Category module access to only essential administrative accounts until a patch is available

# Example: Add CSP headers to web server configuration (Apache)
# Add to .htaccess or Apache configuration file
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"

# Example: Nginx CSP configuration
# Add to server block in nginx.conf
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';";