CVE-2025-70231: D-Link DIR-513 Path Traversal Vulnerability

CVE-2025-70231 Overview

A path traversal vulnerability exists in D-Link DIR-513 version 1.10 that allows attackers to access arbitrary files on the affected device. The vulnerability is present in the authentication code handling functionality, specifically when processing POST requests to /goform/formLogin. When the request is routed to /goform/getAuthCode, the firmware fails to properly sanitize the FILECODE parameter, enabling directory traversal attacks.

Critical Impact

Attackers can exploit this path traversal vulnerability to read sensitive files outside the intended directory, potentially exposing configuration files, credentials, and other sensitive system data on affected D-Link DIR-513 routers.

Affected Products

• D-Link DIR-513 version 1.10
• D-Link DIR-513 firmware with vulnerable /goform/getAuthCode endpoint

Discovery Timeline

• 2026-03-05 - CVE-2025-70231 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2025-70231

Vulnerability Analysis

This path traversal vulnerability arises from insufficient input validation in the D-Link DIR-513 router's web interface. When a user submits a POST request to the /goform/formLogin endpoint for authentication purposes, the request handling code subsequently calls /goform/getAuthCode to process verification codes. The FILECODE parameter passed to this endpoint is not properly filtered or sanitized before being used in file system operations.

The lack of input sanitization allows an attacker to inject directory traversal sequences (such as ../) into the FILECODE parameter. This enables navigation outside the intended directory structure, potentially allowing access to sensitive files stored elsewhere on the device's file system.

Root Cause

The root cause of this vulnerability is improper input validation in the /goform/getAuthCode handler function. The firmware accepts user-supplied input for the FILECODE parameter and uses it directly in file path operations without:

• Stripping or rejecting directory traversal characters (../, ..\\)
• Validating that the resulting path remains within the expected directory
• Implementing a whitelist of allowed file names or paths
• Canonicalizing the path before use

Attack Vector

An attacker can exploit this vulnerability remotely by sending specially crafted HTTP POST requests to the router's web interface. The attack does not require authentication if the vulnerable endpoint is accessible. By manipulating the FILECODE parameter with path traversal sequences, the attacker can traverse the file system and read files outside the intended directory.

The vulnerability manifests when processing authentication-related POST requests. An attacker would craft a malicious POST request to /goform/formLogin with a FILECODE parameter containing directory traversal sequences such as ../../../../etc/passwd. The server processes this input without sanitization, allowing access to arbitrary files on the system. For detailed technical analysis, refer to the GitHub CVE Report Repository.

Detection Methods for CVE-2025-70231

Indicators of Compromise

• HTTP POST requests to /goform/formLogin or /goform/getAuthCode containing ../ or encoded variants in the FILECODE parameter
• Unusual access patterns to the router's web management interface from external IP addresses
• Log entries showing file access attempts outside normal web application directories
• Attempts to access sensitive system files such as /etc/passwd, /etc/shadow, or configuration files

Detection Strategies

• Monitor web server logs for requests containing directory traversal patterns (../, %2e%2e%2f, %252e%252e%252f) in POST parameters
• Implement intrusion detection rules to alert on path traversal attempts targeting D-Link router endpoints
• Deploy network monitoring to detect suspicious traffic patterns to router management interfaces
• Use web application firewall (WAF) rules to block requests containing path traversal sequences

Monitoring Recommendations

• Enable verbose logging on D-Link router administration interfaces where available
• Monitor network traffic for unusual POST requests to /goform/* endpoints
• Implement alerting for access attempts to the router management interface from untrusted networks
• Review router access logs regularly for signs of exploitation attempts

How to Mitigate CVE-2025-70231

Immediate Actions Required

• Restrict access to the D-Link DIR-513 web management interface to trusted internal networks only
• Disable remote administration if not required for operations
• Implement firewall rules to block external access to the router's management ports (typically port 80/443)
• Monitor the D-Link Security Bulletin for firmware updates addressing this vulnerability

Patch Information

Check the D-Link Product Information page for firmware updates that address this path traversal vulnerability. Ensure the router is running the latest available firmware version from D-Link. If the device has reached end-of-life status, consider replacing it with a supported model that receives security updates.

Workarounds

• Configure access control lists (ACLs) to restrict management interface access to specific trusted IP addresses
• Place the router's management interface on a separate VLAN accessible only to authorized administrators
• Use a VPN for remote administration instead of exposing the management interface directly
• Implement network segmentation to limit the impact if the device is compromised

# Example firewall rule to restrict router management access (adjust for your environment)
# Block external access to router management interface
iptables -A FORWARD -d ROUTER_IP -p tcp --dport 80 -j DROP
iptables -A FORWARD -d ROUTER_IP -p tcp --dport 443 -j DROP
# Allow management access only from trusted admin network
iptables -A FORWARD -s ADMIN_NETWORK/24 -d ROUTER_IP -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -s ADMIN_NETWORK/24 -d ROUTER_IP -p tcp --dport 443 -j ACCEPT