CVE-2025-4452: D-Link DIR-619L Buffer Overflow Vulnerability

CVE-2025-4452 Overview

A critical buffer overflow vulnerability has been identified in the D-Link DIR-619L wireless router firmware version 2.04B04. The vulnerability exists in the formSetWizard2 function, where improper handling of the curTime argument allows an attacker to trigger a buffer overflow condition. This vulnerability can be exploited remotely over the network, potentially allowing attackers to execute arbitrary code or cause denial of service on affected devices.

Of significant concern is that this vulnerability affects a product that has reached end-of-life status and is no longer supported by D-Link. Users of affected devices will not receive official patches and must consider device replacement or alternative mitigations.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability to potentially achieve code execution or crash the device. The affected D-Link DIR-619L router is end-of-life with no vendor patches available.

Affected Products

• D-Link DIR-619L Hardware
• D-Link DIR-619L Firmware version 2.04B04
• Earlier firmware versions may also be affected

Discovery Timeline

• 2025-05-09 - CVE-2025-4452 published to NVD
• 2025-05-13 - Last updated in NVD database

Technical Details for CVE-2025-4452

Vulnerability Analysis

This buffer overflow vulnerability (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer, CWE-120: Buffer Copy without Checking Size of Input) occurs in the formSetWizard2 function of the D-Link DIR-619L router firmware. The function fails to properly validate the size of the curTime parameter before copying it into a fixed-size buffer, allowing an attacker to overflow the buffer with malicious data.

The vulnerability is remotely exploitable over the network without requiring user interaction. An authenticated attacker with low-level privileges can manipulate the curTime argument to overflow the buffer, potentially overwriting adjacent memory structures including return addresses or function pointers. This could lead to arbitrary code execution with the privileges of the web server process running on the router.

Root Cause

The root cause of this vulnerability is the absence of proper bounds checking when handling the curTime parameter within the formSetWizard2 function. The firmware code copies user-supplied input into a fixed-size buffer without verifying that the input length does not exceed the buffer capacity. This classic buffer overflow pattern allows attackers to write beyond the allocated memory region.

Attack Vector

The attack is conducted remotely over the network, targeting the web management interface of the DIR-619L router. An attacker with network access to the device's administrative interface can send specially crafted HTTP requests containing an oversized curTime parameter to the formSetWizard2 handler. The malicious request triggers the buffer overflow condition when the firmware processes the input.

The attack requires low privileges, indicating that basic authentication to the device may be required. However, once authenticated (potentially with default or weak credentials), the attacker can exploit this vulnerability to potentially gain full control of the router, intercept network traffic, or use the compromised device as a pivot point for further attacks on the internal network.

Technical details and proof-of-concept information are available in the GitHub PoC Repository. Additional vulnerability intelligence can be found at VulDB #308066.

Detection Methods for CVE-2025-4452

Indicators of Compromise

• Unusual HTTP POST requests to the router's web interface containing abnormally long curTime parameter values
• Router crashes or unexpected reboots that may indicate exploitation attempts
• Anomalous network traffic originating from the router to external IP addresses
• Changes to router configuration that were not authorized by administrators

Detection Strategies

• Monitor network traffic for HTTP requests targeting the DIR-619L management interface with oversized parameters
• Implement intrusion detection system (IDS) rules to detect buffer overflow patterns in HTTP traffic to embedded devices
• Review router logs for repeated authentication attempts followed by configuration changes
• Deploy network monitoring to identify unexpected outbound connections from router IP addresses

Monitoring Recommendations

• Establish baseline network behavior for DIR-619L devices and alert on deviations
• Configure SIEM systems to correlate events related to router management interface access
• Implement network segmentation to isolate vulnerable router management interfaces from untrusted networks
• Monitor for firmware modification attempts or unauthorized configuration backups

How to Mitigate CVE-2025-4452

Immediate Actions Required

• Restrict access to the router's administrative interface to trusted IP addresses only
• Disable remote management access from the WAN interface immediately
• Change default administrative credentials to strong, unique passwords
• Consider replacing the end-of-life DIR-619L with a supported device that receives security updates
• Isolate the affected device on a separate network segment if replacement is not immediately possible

Patch Information

D-Link has confirmed that the DIR-619L router is an end-of-life product and will not receive security patches for this vulnerability. The vendor was contacted about this disclosure but no remediation is expected. Users are strongly encouraged to replace affected devices with currently supported hardware models.

For more information, visit the D-Link Official Website to explore supported replacement options.

Workarounds

• Disable the web management interface entirely if not required for operations
• Implement firewall rules to block external access to the router's management ports (typically TCP port 80/443)
• Use a VPN solution to access the management interface if remote administration is required
• Deploy a next-generation firewall or IPS in front of the vulnerable device to filter malicious requests
• Consider open-source firmware alternatives (e.g., DD-WRT, OpenWrt) if compatible with the hardware

# Example iptables rules to restrict management access (apply on upstream firewall)
# Block external access to router management interface
iptables -A FORWARD -d 192.168.0.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.0.1 -p tcp --dport 443 -j DROP

# Allow management access only from trusted admin subnet
iptables -I FORWARD -s 192.168.1.0/24 -d 192.168.0.1 -p tcp --dport 80 -j ACCEPT