CVE-2025-6615: D-Link DIR-619L Buffer Overflow Vulnerability

CVE-2025-6615 Overview

CVE-2025-6615 is a stack-based buffer overflow vulnerability in the D-Link DIR-619L wireless router running firmware version 2.06B01. The flaw resides in the formAutoDetecWAN_wizard4 function within /goform/formAutoDetecWAN_wizard4. Attackers can exploit the issue by manipulating the curTime argument, triggering memory corruption on the stack. The vulnerability is remotely exploitable and a public exploit has been disclosed. D-Link has confirmed the DIR-619L is end-of-life and will not receive a patch. The weakness is tracked 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 on unsupported D-Link DIR-619L routers, leading to arbitrary code execution or full device compromise.

Affected Products

D-Link DIR-619L hardware router (end-of-life)
D-Link DIR-619L firmware version 2.06B01
Any deployment still operating the unsupported DIR-619L line

Discovery Timeline

2025-06-25 - CVE-2025-6615 published to NVD
2025-07-14 - Last updated in NVD database

Technical Details for CVE-2025-6615

Vulnerability Analysis

The vulnerability exists in the web administration interface of the D-Link DIR-619L router. The handler for /goform/formAutoDetecWAN_wizard4 processes the curTime HTTP parameter without enforcing length validation. The function formAutoDetecWAN_wizard4 copies the attacker-controlled value into a fixed-size stack buffer, overflowing adjacent memory regions including the saved return address.

Successful exploitation corrupts the call stack, allowing an attacker to redirect execution flow. On MIPS-based embedded devices like the DIR-619L, this typically results in arbitrary code execution under the privileges of the router's web service, which generally runs as root.

Because the DIR-619L is no longer supported, exposed devices remain permanently vulnerable. The public disclosure of proof-of-concept material on GitHub increases the likelihood of opportunistic scanning and exploitation against internet-facing management interfaces.

Root Cause

The root cause is unbounded copying of the curTime request parameter into a stack buffer inside the formAutoDetecWAN_wizard4 handler. The firmware fails to validate the parameter length before invoking an unsafe string copy operation. This is a classic [CWE-119] memory boundary violation common in legacy embedded HTTP servers.

Attack Vector

An authenticated attacker with low privileges sends a crafted HTTP POST request to /goform/formAutoDetecWAN_wizard4 containing an oversized curTime value. The request can be delivered remotely over the network where the web management interface is reachable. The malformed payload overflows the stack buffer, overwrites the saved return address, and redirects execution to attacker-controlled shellcode or a return-oriented programming chain.

The vulnerability mechanics are documented in the GitHub Vulnerability Documentation and the corresponding GitHub PoC for D-Link6.

Detection Methods for CVE-2025-6615

Indicators of Compromise

HTTP requests targeting /goform/formAutoDetecWAN_wizard4 containing abnormally long curTime parameter values
Unexpected reboots, crashes, or watchdog resets of DIR-619L devices following inbound HTTP traffic
Outbound connections from the router to unfamiliar hosts on non-standard ports
Configuration changes or new administrator sessions originating from external IP addresses

Detection Strategies

Inspect web server logs for POST requests to /goform/formAutoDetecWAN_wizard4 and flag entries with curTime lengths exceeding typical timestamp values
Deploy network intrusion detection signatures that match oversized curTime parameters in HTTP traffic destined for D-Link management interfaces
Correlate router crash events with preceding HTTP traffic to identify exploitation attempts

Monitoring Recommendations

Continuously monitor management interface exposure by scanning the perimeter for reachable D-Link administration ports
Forward router syslog data to a centralized logging platform for anomaly analysis
Alert on any traffic to legacy D-Link /goform/ endpoints from untrusted networks

How to Mitigate CVE-2025-6615

Immediate Actions Required

Remove the DIR-619L from service and replace it with a currently supported router model, as D-Link will not issue a patch
If immediate replacement is not feasible, disable remote management and restrict the web interface to a trusted management VLAN
Block external access to /goform/formAutoDetecWAN_wizard4 at the network perimeter
Audit administrator credentials and rotate any shared secrets used on the device

Patch Information

No patch is available. D-Link has classified the DIR-619L as end-of-life and explicitly states that unsupported products will not receive security updates. Refer to the D-Link Official Website for the current list of supported replacement models. Additional vulnerability metadata is available at VulDB #313833.

Workarounds

Disable the WAN setup wizard endpoints on the administrative interface if configurable
Segment the router onto a management-only network unreachable from user or guest subnets
Enforce strong, unique administrator credentials to limit the low-privilege precondition required for exploitation
Replace the device with a vendor-supported model that receives security updates

bash

# Example: block external access to the vulnerable endpoint at an upstream firewall
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 \
  -m string --string "/goform/formAutoDetecWAN_wizard4" --algo bm -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 \
  -m string --string "/goform/formAutoDetecWAN_wizard4" --algo bm -j DROP