CVE-2025-4451: D-Link DIR-619L Buffer Overflow Vulnerability

CVE-2025-4451 Overview

CVE-2025-4451 is a buffer overflow vulnerability in the D-Link DIR-619L wireless router running firmware version 2.04B04. The flaw resides in the formSetWAN_Wizard52 function, where manipulation of the curTime argument causes a buffer overflow condition. Attackers can exploit this issue remotely over the network. The D-Link DIR-619L has reached end-of-life status and no longer receives security updates from the vendor. Affected device owners must replace the hardware or apply network-level mitigations. The vulnerability is tracked under [CWE-119] and [CWE-120], covering improper restriction of operations within memory buffer bounds.

Critical Impact
Remote attackers with low privileges can trigger a buffer overflow in the WAN configuration handler, leading to potential code execution or device compromise on unsupported D-Link DIR-619L routers.

Affected Products

D-Link DIR-619L hardware router
D-Link DIR-619L firmware version 2.04B04
End-of-life D-Link consumer routers no longer maintained by the vendor

Discovery Timeline

2025-05-09 - CVE-2025-4451 published to NVD
2025-05-13 - Last updated in NVD database

Technical Details for CVE-2025-4451

Vulnerability Analysis

The vulnerability exists in the formSetWAN_Wizard52 function of the DIR-619L web management interface. This function processes WAN configuration data submitted through the router setup wizard. The curTime parameter is copied into a fixed-size stack buffer without proper length validation. An attacker who submits an oversized curTime value overflows the buffer and corrupts adjacent memory.

Memory corruption in router firmware typically enables hijacking of program control flow. Successful exploitation can result in arbitrary code execution on the device with the privileges of the web server process. Routers compromised through this class of vulnerability are commonly enrolled into botnets or used as pivots into internal networks.

The vendor has confirmed that the affected product line is no longer supported. No patched firmware will be released for the DIR-619L.

Root Cause

The root cause is missing bounds checking on the curTime input parameter inside formSetWAN_Wizard52. The function uses an unsafe string copy operation that does not enforce the destination buffer size. This pattern matches [CWE-120] classic buffer overflow and [CWE-119] improper memory buffer restriction.

Attack Vector

Attackers reach the vulnerability through the router's HTTP management interface. Exploitation requires the attacker to submit a crafted POST request to the wizard endpoint with an oversized curTime value. The CVSS vector indicates low privileges are required, suggesting the attacker needs valid session credentials or access to an authenticated session. Devices exposing the management interface to the WAN side significantly increase exposure.

The vulnerability mechanism is a classic stack-based buffer overflow triggered by unbounded user input. No verified public exploit code or proof-of-concept binary has been confirmed beyond the technical write-up referenced by VulDB CTI ID #308065 and the GitHub PoC Repository.

Detection Methods for CVE-2025-4451

Indicators of Compromise

HTTP POST requests to the router management interface targeting wizard endpoints with abnormally long curTime parameter values
Unexpected reboots, crashes, or process restarts on DIR-619L devices following inbound HTTP traffic
Outbound connections from the router to unfamiliar IP addresses or command-and-control infrastructure
DNS configuration changes or unauthorized firmware-level modifications on the device

Detection Strategies

Inspect web server access logs on the router for requests containing oversized parameter values in WAN wizard form submissions
Deploy network intrusion detection signatures that flag HTTP requests with parameter lengths exceeding expected bounds for D-Link administrative endpoints
Monitor for anomalous traffic patterns originating from end-of-life consumer routers within the network

Monitoring Recommendations

Track all administrative access to the DIR-619L web interface and alert on requests from untrusted sources
Capture network flow data from router uplinks to identify command-and-control beaconing
Audit perimeter firewall rules to confirm the router management interface is not exposed to the internet

How to Mitigate CVE-2025-4451

Immediate Actions Required

Replace the D-Link DIR-619L with a supported router model that receives security updates from the vendor
Disable remote management on the WAN interface immediately if replacement is not yet possible
Restrict LAN-side access to the router administration interface to specific trusted hosts or VLANs
Change default administrative credentials and use a strong unique password on the device

Patch Information

No patch will be released. The D-Link DIR-619L is end-of-life and no longer supported by the manufacturer. Vendor confirmation is available on the D-Link Official Website. Replacement of the hardware is the only complete remediation.

Workarounds

Place the router behind a separate firewall and block external access to TCP ports 80 and 443 on the device
Segment the affected router onto an isolated network segment with no access to sensitive internal resources
Disable the WAN setup wizard functionality if the router configuration allows it
Monitor the device for signs of compromise and decommission it as soon as a replacement is operational

bash

# Example: block external access to the router management interface at the upstream firewall
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -j DROP

# Restrict management access to a single trusted admin workstation
iptables -A FORWARD -p tcp -s <admin_ip> -d <router_ip> --dport 80 -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP