CVE-2018-25157: Phraseanet Stored XSS Vulnerability

CVE-2018-25157 Overview

CVE-2018-25157 is a stored cross-site scripting (XSS) vulnerability in Phraseanet 4.0.3, a digital asset management (DAM) application. The vulnerability allows authenticated users to inject malicious scripts through crafted file names during document uploads. Attackers can upload files with embedded SVG scripts that execute in the browser when the file is viewed, potentially stealing session cookies or redirecting users to malicious sites.

Critical Impact

Authenticated attackers can inject persistent malicious scripts that execute in the context of other users' sessions, enabling session hijacking, credential theft, and phishing attacks against Phraseanet users.

Affected Products

• Phraseanet 4.0.3

Discovery Timeline

• 2026-02-11 - CVE CVE-2018-25157 published to NVD
• 2026-02-11 - Last updated in NVD database

Technical Details for CVE-2018-25157

Vulnerability Analysis

This stored XSS vulnerability (CWE-79) exists in the document upload functionality of Phraseanet 4.0.3. The application fails to properly sanitize file names when users upload documents to the digital asset management system. When a malicious actor uploads a file containing JavaScript code embedded within an SVG format or through specially crafted file name characters, the payload is stored on the server and executed whenever another user views or accesses the uploaded file.

The attack requires authentication to upload files but does not require administrative privileges, making it accessible to any user with upload permissions. Once the malicious file is stored, the XSS payload persists and can affect multiple victims over time.

Root Cause

The root cause of this vulnerability is improper input validation and output encoding in the file upload handler. Phraseanet 4.0.3 does not adequately sanitize user-supplied file names before storing them in the database and rendering them in the web interface. This allows attackers to inject JavaScript code that bypasses input filters, particularly through SVG file uploads that can contain embedded script elements.

Attack Vector

The attack vector is network-based and requires user interaction for successful exploitation. An authenticated attacker uploads a file with a malicious file name or an SVG file containing embedded JavaScript. When another user browses the document library and views the file listing or preview, the browser renders the malicious content, executing the attacker's script in the context of the victim's session.

The exploitation flow involves:

1. Attacker authenticates to Phraseanet with valid credentials
2. Attacker creates a file with malicious JavaScript embedded in the filename or as SVG content
3. Attacker uploads the file through the document upload interface
4. Victim user accesses the file listing or views the document
5. Browser executes the malicious script, potentially sending session cookies to attacker-controlled servers

For detailed technical information about this vulnerability, see the Exploit-DB #46935 entry and the VulnCheck Advisory on Phraseanet.

Detection Methods for CVE-2018-25157

Indicators of Compromise

• Uploaded files with suspicious characters or JavaScript syntax in file names (e.g., <script>, onerror=, onload=)
• SVG files containing <script> tags or JavaScript event handlers in the uploads directory
• Unusual outbound connections from user browsers to external domains after accessing the document library
• Session token anomalies or unexpected session activity patterns

Detection Strategies

• Implement web application firewall (WAF) rules to detect XSS payloads in file upload requests
• Monitor application logs for file uploads containing suspicious patterns such as <script>, javascript:, or SVG event handlers
• Deploy browser-based XSS detection tools to identify script execution from file content
• Review uploaded file metadata and names for encoded JavaScript payloads

Monitoring Recommendations

• Enable detailed logging for all file upload operations in Phraseanet
• Configure security information and event management (SIEM) alerts for patterns matching XSS attack signatures in HTTP requests
• Implement content security policy (CSP) headers to detect and report inline script execution attempts
• Regularly audit uploaded files for potentially malicious content

How to Mitigate CVE-2018-25157

Immediate Actions Required

• Upgrade Phraseanet to the latest available version from the Phraseanet Download Page
• Review and remove any suspicious files with unusual file names from the document repository
• Implement strict input validation on all file upload endpoints
• Configure Content Security Policy (CSP) headers to prevent inline script execution

Patch Information

Users should update to a patched version of Phraseanet. Check the Phraseanet Official Site for the latest security updates and release information. Review the VulnCheck Advisory on Phraseanet for specific remediation guidance.

Workarounds

• Implement server-side file name sanitization to strip special characters and HTML/JavaScript syntax before storage
• Deploy a web application firewall (WAF) with XSS protection rules to filter malicious upload requests
• Restrict file upload permissions to trusted users only until a patch can be applied
• Configure the application to serve uploaded files with Content-Disposition: attachment headers to prevent in-browser rendering

# Example Apache configuration to add security headers
<IfModule mod_headers.c>
    # Content Security Policy to mitigate XSS
    Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'"
    
    # Force download for uploaded files in assets directory
    <Directory "/var/www/phraseanet/uploads">
        Header set Content-Disposition "attachment"
        Header set X-Content-Type-Options "nosniff"
    </Directory>
</IfModule>