CVE-2026-6497: TinyFileManager SSRF Vulnerability

CVE-2026-6497 Overview

A Server-Side Request Forgery (SSRF) vulnerability has been identified in prasathmani TinyFileManager up to version 2.6. The vulnerability exists within the File Upload Handler component, specifically in the /filemanager.php?p=&ajax=true&type=upload endpoint. Manipulation of the uploadurl argument allows attackers to conduct SSRF attacks, potentially enabling access to internal services, bypassing firewalls, or exfiltrating sensitive data from the target system's network.

Critical Impact

Remote attackers with low privileges can exploit this SSRF vulnerability to make arbitrary server-side requests, potentially accessing internal resources, cloud metadata endpoints, or sensitive services not intended to be publicly accessible.

Affected Products

• prasathmani TinyFileManager up to version 2.6
• TinyFileManager File Upload Handler component (/filemanager.php)

Discovery Timeline

• 2026-04-17 - CVE-2026-6497 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-6497

Vulnerability Analysis

This vulnerability is classified as Server-Side Request Forgery (SSRF) under CWE-918. The flaw resides in the File Upload Handler functionality of TinyFileManager, which processes upload requests through the /filemanager.php endpoint when specific query parameters are provided (p=&ajax=true&type=upload).

The vulnerability occurs because the application fails to properly validate or sanitize the uploadurl parameter before making server-side HTTP requests. When a user provides a URL through this parameter, the server fetches content from that URL without adequate restrictions, allowing an attacker to direct the server to make requests to arbitrary destinations.

This SSRF vulnerability can be exploited remotely with low privileges required, making it accessible to authenticated users of the file manager application. The exploit has been publicly disclosed and documented, increasing the risk of active exploitation in the wild.

Root Cause

The root cause of this vulnerability is insufficient input validation on the uploadurl parameter within the File Upload Handler. The application does not implement proper URL validation, allowlisting, or blocklisting mechanisms to restrict the destinations that can be requested. This allows attackers to supply arbitrary URLs, including internal IP addresses, localhost references, cloud metadata endpoints (such as 169.254.169.254), or other sensitive internal resources.

Attack Vector

The attack is conducted remotely over the network. An authenticated attacker with low-level privileges can craft malicious requests to the vulnerable endpoint, specifying internal or sensitive URLs in the uploadurl parameter. The server then processes these requests on behalf of the attacker, effectively acting as a proxy.

Common exploitation scenarios include:

• Accessing cloud instance metadata services to retrieve credentials or configuration data
• Port scanning internal networks to discover additional services
• Accessing internal APIs or administrative interfaces not exposed to the internet
• Reading local files if the URL handler supports file:// protocol
• Bypassing IP-based access controls and firewalls

The vulnerability mechanism involves manipulating the uploadurl parameter in requests to the /filemanager.php endpoint. When processing upload operations with the ajax=true&type=upload parameters, the application fetches content from user-supplied URLs without adequate validation. This allows attackers to craft requests targeting internal services, cloud metadata endpoints, or other restricted resources that the server can access. Technical details and proof-of-concept information are available through the VulDB Vulnerability Entry.

Detection Methods for CVE-2026-6497

Indicators of Compromise

• Unusual outbound HTTP requests from web servers to internal IP ranges (10.x.x.x, 172.16.x.x, 192.168.x.x)
• Requests to cloud metadata endpoints (169.254.169.254) originating from web application servers
• HTTP access logs showing repeated requests to /filemanager.php with uploadurl parameters containing internal addresses or localhost references
• Network traffic anomalies indicating the web server is accessing unexpected internal services

Detection Strategies

• Monitor web application firewall (WAF) logs for requests to /filemanager.php containing suspicious uploadurl values
• Implement network segmentation monitoring to detect web servers attempting to access internal services they should not normally reach
• Deploy intrusion detection rules to flag SSRF patterns in HTTP request parameters targeting internal IP ranges or metadata endpoints
• Review TinyFileManager access logs for unusual file upload activity with external URL sources

Monitoring Recommendations

• Enable detailed logging on TinyFileManager installations and forward logs to centralized SIEM systems
• Configure alerts for any outbound connections from web servers to RFC 1918 private IP ranges or cloud metadata addresses
• Implement network flow analysis to baseline normal web server behavior and detect anomalous internal connections
• Monitor for increased latency or errors in file upload operations that might indicate exploitation attempts

How to Mitigate CVE-2026-6497

Immediate Actions Required

• Review and restrict access to TinyFileManager installations, limiting authenticated users to only trusted personnel
• Implement network-level controls to prevent the web server from making connections to internal IP ranges and cloud metadata endpoints
• Consider temporarily disabling the remote URL upload functionality if not required for business operations
• Deploy web application firewall rules to block requests containing suspicious uploadurl parameter values

Patch Information

At the time of disclosure, the vendor (prasathmani) was contacted regarding this vulnerability but did not respond. No official patch has been released. Organizations should monitor the official TinyFileManager repository for future security updates and consider implementing the workarounds described below until a patch becomes available.

Workarounds

• Disable the URL-based upload functionality by modifying the TinyFileManager configuration or code to remove the uploadurl handling capability
• Implement input validation at the application or web server level to allowlist only trusted external domains for URL-based uploads
• Deploy network segmentation to isolate web servers running TinyFileManager from sensitive internal resources
• Use a reverse proxy or WAF with SSRF protection rules to filter malicious requests before they reach the application

# Example: Block internal IP ranges at the firewall level for the web server
# This prevents the web server from making SSRF requests to internal resources
iptables -A OUTPUT -p tcp -d 10.0.0.0/8 -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -p tcp -d 172.16.0.0/12 -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -p tcp -d 192.168.0.0/16 -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -p tcp -d 169.254.169.254 -m owner --uid-owner www-data -j DROP