CVE-2025-13810: Webstack-guns Path Traversal Flaw

CVE-2025-13810 Overview

A path traversal vulnerability has been identified in jsnjfz WebStack-Guns version 1.0. This security flaw affects the renderPicture function within the file src/main/java/com/jsnjfz/manage/modular/system/controller/KaptchaController.java. Through improper input validation, an attacker can manipulate file paths to traverse directories and potentially access files outside the intended directory structure. The vulnerability can be exploited remotely without authentication, and a public exploit has been disclosed.

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 system.

Affected Products

• jsnjfz WebStack-Guns version 1.0
• Systems running WebStack-Guns with the vulnerable KaptchaController.java component
• Java-based web applications utilizing the affected file rendering functionality

Discovery Timeline

• December 1, 2025 - CVE-2025-13810 published to NVD
• December 4, 2025 - Last updated in NVD database

Technical Details for CVE-2025-13810

Vulnerability Analysis

This path traversal vulnerability (CWE-22) exists in the renderPicture function of the KaptchaController.java file. The vulnerable function fails to properly sanitize user-supplied input before using it to construct file paths, allowing attackers to navigate outside the intended directory structure using directory traversal sequences such as ../. This can enable unauthorized access to sensitive files on the server's filesystem.

The vulnerability is remotely exploitable over the network with low attack complexity. No privileges or user interaction are required to exploit this flaw, making it accessible to unauthenticated attackers. The primary impact is confidentiality-related, as attackers can read arbitrary files but cannot modify or delete them through this vulnerability.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and sanitization within the renderPicture function. The application accepts user-controlled input for file path construction without properly validating or filtering path traversal sequences. This allows malicious input containing ../ sequences or similar path manipulation characters to escape the intended directory boundary and access files elsewhere on the filesystem.

Attack Vector

The attack is conducted remotely over the network by sending crafted HTTP requests to the vulnerable endpoint. An attacker constructs a request containing path traversal sequences (such as ../../../etc/passwd on Unix-like systems or ..\..\..\windows\system.ini on Windows) targeting the renderPicture function. When the application processes this malicious input without proper sanitization, it resolves the traversal sequences and attempts to read the specified file, returning its contents to the attacker.

The vulnerability manifests in the renderPicture function of KaptchaController.java where user-supplied input is used to construct file paths without adequate validation. For detailed technical information and proof-of-concept, refer to the GitHub Report on Path Traversal.

Detection Methods for CVE-2025-13810

Indicators of Compromise

• HTTP requests to the KaptchaController endpoint containing path traversal sequences such as ../, ..%2f, or %2e%2e/
• Unusual file access patterns in web server logs showing requests for files outside the web root directory
• Access log entries showing requests for sensitive system files like /etc/passwd, configuration files, or credential stores
• Error logs indicating file access attempts to unexpected directories

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block path traversal patterns in HTTP requests
• Configure intrusion detection systems (IDS) to alert on requests containing encoded or decoded directory traversal sequences
• Enable detailed logging on the WebStack-Guns application to capture all file access attempts
• Deploy endpoint detection solutions to monitor for unauthorized file reads on the server

Monitoring Recommendations

• Monitor web server access logs for suspicious patterns targeting the renderPicture endpoint
• Set up alerts for requests containing common path traversal strings and their encoded variants
• Review application logs for file access errors indicating traversal attempts outside allowed directories
• Implement file integrity monitoring on sensitive directories to detect unauthorized access attempts

How to Mitigate CVE-2025-13810

Immediate Actions Required

• Restrict network access to the affected WebStack-Guns application to trusted IP addresses only
• Implement input validation at the web application firewall level to block path traversal sequences
• Review and audit all file access operations within the application for similar vulnerabilities
• Consider disabling the renderPicture functionality if not essential for business operations until a patch is available

Patch Information

No official patch is currently available from the vendor. The vendor was contacted regarding this vulnerability but did not respond. Organizations using WebStack-Guns should implement the recommended workarounds and monitor for any future updates. For additional details, see the VulDB entry #333820.

Workarounds

• Implement strict input validation to reject any file path parameters containing ../, encoded variants, or null bytes
• Configure the application to use a whitelist of allowed file paths rather than accepting arbitrary user input
• Deploy a web application firewall with rules to filter path traversal attack patterns
• Run the application with minimal filesystem permissions to limit the impact of successful exploitation

# Example WAF rule configuration to block path traversal
# Add to your web application firewall or reverse proxy configuration

# Block common path traversal patterns
SecRule REQUEST_URI "../" "id:1000,phase:1,deny,status:403,msg:'Path Traversal Attempt'"
SecRule REQUEST_URI "..%2f" "id:1001,phase:1,deny,status:403,msg:'Encoded Path Traversal'"
SecRule REQUEST_URI "%2e%2e/" "id:1002,phase:1,deny,status:403,msg:'Double Encoded Traversal'"