CVE-2025-6614: D-Link DIR-619L Buffer Overflow Flaw

CVE-2025-6614 Overview

CVE-2025-6614 is a stack-based buffer overflow vulnerability in the D-Link DIR-619L router running firmware version 2.06B01. The flaw resides in the formSetWANType_Wizard5 function within /goform/formSetWANType_Wizard5, where the curTime parameter is processed without proper bounds checking. Remote attackers can exploit this issue over the network to corrupt memory and potentially execute arbitrary code on the device. The vulnerability has been publicly disclosed and affects an end-of-life product that no longer receives security updates from the vendor. The flaw is classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer).

Critical Impact
Remote attackers can trigger a stack-based buffer overflow through the curTime parameter, leading to memory corruption and potential code execution on unsupported D-Link DIR-619L routers.

Affected Products

D-Link DIR-619L hardware router
D-Link DIR-619L firmware version 2.06B01
End-of-life D-Link consumer router product line (no vendor support available)

Discovery Timeline

2025-06-25 - CVE-2025-6614 published to the National Vulnerability Database
2025-07-16 - Last updated in NVD database

Technical Details for CVE-2025-6614

Vulnerability Analysis

The vulnerability exists in the web-based administration interface of the D-Link DIR-619L router. Specifically, the formSetWANType_Wizard5 handler processes HTTP requests sent to /goform/formSetWANType_Wizard5 as part of the WAN configuration wizard. When the handler reads the curTime argument from the incoming request, it copies the user-supplied value into a fixed-size stack buffer without validating the input length. An attacker who submits an oversized curTime value overflows this buffer and overwrites adjacent stack data, including saved return addresses.

This flaw maps to [CWE-119], a classic memory safety failure common in embedded MIPS-based router firmware. Successful exploitation can lead to denial of service through process crash or arbitrary code execution within the context of the web server process, which typically runs with elevated privileges on consumer routers. The EPSS data indicates a probability of approximately 0.825% with a percentile of 74.86, reflecting moderate near-term exploitation interest.

Root Cause

The root cause is the absence of length validation on attacker-controlled input before it is copied into a stack-allocated buffer. The handler trusts the size of the curTime parameter sent in the HTTP request body, using unsafe string-copy semantics typical of legacy C code in embedded web stacks such as boa or goahead derivatives used in D-Link firmware.

Attack Vector

Exploitation requires network access to the router's administrative web interface and a low-privilege authenticated context. An attacker crafts an HTTP POST request to /goform/formSetWANType_Wizard5 containing a curTime parameter with a payload longer than the destination buffer. The oversized value corrupts the stack frame, enabling control-flow hijacking on devices without modern exploit mitigations such as stack canaries or ASLR. Public proof-of-concept documentation is referenced in the GitHub Vulnerability Report and VulDB #313832.

Detection Methods for CVE-2025-6614

Indicators of Compromise

HTTP POST requests to /goform/formSetWANType_Wizard5 containing abnormally long curTime parameter values
Unexpected reboots, crashes, or service restarts of the router's httpd or web management process
Outbound connections from the router to unknown IP addresses, suggesting post-exploitation activity
Modified DNS settings, firewall rules, or administrative credentials on the device

Detection Strategies

Inspect network traffic destined for the router's management interface for oversized form parameters targeting /goform/ endpoints
Deploy intrusion detection signatures that flag HTTP requests where curTime exceeds expected length boundaries
Monitor for repeated requests to the WAN setup wizard endpoints from internal hosts that would not normally configure the router

Monitoring Recommendations

Log all administrative access attempts to consumer routers from internal network segments
Correlate router crash events with preceding HTTP traffic to identify exploitation attempts
Alert on any new device that begins probing /goform/ URIs on internal infrastructure

How to Mitigate CVE-2025-6614

Immediate Actions Required

Decommission and replace the D-Link DIR-619L, since the device is end-of-life and no patch will be issued by the vendor
Disable remote management on the WAN interface to limit exposure to internet-based attackers
Restrict access to the router's web administration interface to a dedicated management VLAN or trusted hosts only
Rotate administrative credentials and review router configuration for unauthorized changes

Patch Information

No official patch is available. D-Link has confirmed that the DIR-619L is no longer supported by the maintainer, and this vulnerability will not be remediated through a firmware update. Affected organizations must migrate to a currently supported router platform. Refer to the D-Link Official Site for current product offerings.

Workarounds

Place the router behind an upstream firewall that filters inbound HTTP requests to the management interface
Segment the router from sensitive network resources to limit blast radius if the device is compromised
Disable the WAN setup wizard endpoints through access control lists where the router firmware permits

bash

# Example: block external access to the router management interface using an 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 host
iptables -A FORWARD -p tcp -s <admin_host_ip> -d <router_ip> --dport 80 -j ACCEPT