CVE-2026-2216: WeRSS Path Traversal Vulnerability

CVE-2026-2216 Overview

A path traversal vulnerability has been discovered in rachelos WeRSS we-mp-rss up to version 1.4.8. The vulnerability exists in the download_export_file function within the apis/tools.py file. By manipulating the filename argument, an attacker can traverse directory paths and potentially access arbitrary files on the system. This attack can be launched remotely by authenticated users with low privileges.

Critical Impact

Remote attackers can exploit this path traversal vulnerability to read arbitrary files from the server, potentially exposing sensitive configuration data, credentials, or other confidential information stored on the affected system.

Affected Products

• rachelos WeRSS we-mp-rss versions up to 1.4.8

Discovery Timeline

• 2026-02-09 - CVE-2026-2216 published to NVD
• 2026-02-09 - Last updated in NVD database

Technical Details for CVE-2026-2216

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Path Traversal), which occurs when an application uses external input to construct a pathname that should be within a restricted directory, but fails to properly neutralize special elements that could cause the pathname to resolve outside the intended location.

In the case of WeRSS we-mp-rss, the download_export_file function in apis/tools.py accepts a filename parameter that is not properly sanitized before being used to access files on the filesystem. This allows an attacker to inject path traversal sequences such as ../ to escape the intended directory and access files elsewhere on the system.

The vulnerability requires network access and low privileges to exploit, meaning an authenticated user can leverage this flaw remotely. While the vulnerability primarily impacts confidentiality by allowing unauthorized file reads, it does not directly affect system integrity or availability.

Root Cause

The root cause of this vulnerability is insufficient input validation and sanitization of the filename parameter in the download_export_file function. The application fails to:

1. Validate that the requested filename does not contain directory traversal sequences
2. Canonicalize the path before accessing the file
3. Verify that the resolved path remains within the expected directory boundary

Without proper path normalization and boundary checking, the application blindly constructs file paths using attacker-controlled input.

Attack Vector

The attack vector is network-based, requiring low privileges and no user interaction. An authenticated attacker can craft malicious requests containing path traversal sequences in the filename parameter to access files outside the intended export directory. For example, using sequences like ../../../etc/passwd could allow reading sensitive system files.

The vulnerability mechanism involves manipulating the filename parameter sent to the download_export_file endpoint. When the server processes this request without proper validation, it constructs a file path that can traverse outside the application's root directory, enabling arbitrary file read access. For detailed technical analysis, see the Notion Analysis on Path Traversal.

Detection Methods for CVE-2026-2216

Indicators of Compromise

• Web server logs showing requests to export endpoints with path traversal sequences (../, ..%2f, ..%252f)
• Unexpected file access attempts outside application directories in system audit logs
• Access logs showing repeated requests to apis/tools.py endpoints with encoded special characters
• Evidence of sensitive file contents being exfiltrated through the export functionality

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block path traversal patterns in request parameters
• Monitor application logs for suspicious filename parameters containing directory traversal sequences
• Deploy intrusion detection system (IDS) signatures for common path traversal attack patterns
• Review access logs for anomalous requests targeting the download_export_file endpoint

Monitoring Recommendations

• Enable detailed logging for all file download operations in the WeRSS application
• Configure file integrity monitoring on sensitive directories to detect unauthorized read attempts
• Set up alerts for HTTP requests containing encoded path traversal characters
• Monitor for unusual patterns of file access that deviate from normal application behavior

How to Mitigate CVE-2026-2216

Immediate Actions Required

• Upgrade rachelos WeRSS we-mp-rss to a patched version when available
• Implement input validation on the filename parameter to reject path traversal sequences
• Restrict file access to a designated export directory using chroot or similar isolation mechanisms
• Deploy WAF rules to block requests containing path traversal patterns

Patch Information

No official patch information is currently available in the CVE data. Monitor the VulDB entry for updates on security patches from the vendor. Organizations should check the rachelos WeRSS repository for security updates addressing this vulnerability.

Workarounds

• Implement server-side input validation to strip or reject path traversal sequences from filename parameters
• Use a whitelist approach to only allow access to specific, pre-approved export files
• Configure the web server to restrict file access to designated directories using appropriate access controls
• Consider deploying a reverse proxy with path normalization to neutralize traversal attempts before they reach the application

# Example: Nginx configuration to block path traversal attempts
location /apis/tools/ {
    if ($request_uri ~* "\.\.") {
        return 403;
    }
    # Additional path normalization
    if ($request_uri ~* "%2e%2e") {
        return 403;
    }
}