CVE-2025-6617 Overview
CVE-2025-6617 is a stack-based buffer overflow vulnerability in the D-Link DIR-619L router running firmware version 2.06B01. The flaw resides in the formAdvanceSetup function within /goform/formAdvanceSetup, where manipulation of the webpage argument corrupts the stack. The vulnerability is exploitable remotely and a public exploit disclosure exists. D-Link no longer supports this device, so no vendor patch will be issued. The weakness is categorized under CWE-119, Improper Restriction of Operations within the Bounds of a Memory Buffer.
Critical Impact
Remote attackers with low privileges can trigger memory corruption in the router's web management interface, potentially leading to arbitrary code execution or denial of service on end-of-life hardware that will not receive a fix.
Affected Products
- D-Link DIR-619L hardware router (end-of-life)
- D-Link DIR-619L firmware version 2.06B01
- All deployments exposing the /goform/formAdvanceSetup endpoint
Discovery Timeline
- 2025-06-25 - CVE-2025-6617 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-6617
Vulnerability Analysis
The DIR-619L web administration interface processes HTTP requests through CGI-style handlers exposed under /goform/. The formAdvanceSetup handler accepts a webpage parameter from user-controlled input and copies it into a fixed-size stack buffer without enforcing length validation. An attacker who can authenticate to the router web interface, or who reaches an authenticated session through default or weak credentials, can submit an oversized webpage value to overwrite adjacent stack memory.
Stack-based overflows of this nature typically corrupt the saved return address or stored frame pointer. On MIPS-based embedded routers like the DIR-619L, this allows control of the program counter and can lead to arbitrary code execution under the privileges of the web server process, often running as root. Public proof-of-concept material has been published on GitHub, increasing the exploitation risk for any device still exposed online.
Root Cause
The root cause is missing bounds checking on the webpage argument inside formAdvanceSetup. The function uses an unsafe string copy operation against a fixed-size local buffer, allowing input length to exceed buffer capacity. This pattern is consistent with CWE-119 and reflects long-standing weaknesses in D-Link's legacy goform handler implementations.
Attack Vector
Exploitation requires network reachability to the router's HTTP management interface and a low-privilege authenticated context. The attacker sends a crafted POST request to /goform/formAdvanceSetup containing an overlong webpage parameter. When the handler copies the parameter into its stack buffer, the overflow occurs and execution flow can be redirected. Because the DIR-619L is end-of-life, devices remain vulnerable indefinitely unless removed from service or isolated from untrusted networks. Refer to the GitHub PoC for Vulnerability and VulDB #313835 Information for additional technical context.
Detection Methods for CVE-2025-6617
Indicators of Compromise
- HTTP POST requests to /goform/formAdvanceSetup containing abnormally long webpage parameter values exceeding typical query string lengths.
- Unexpected reboots, watchdog resets, or crashes of the router's httpd process logged in syslog or remote logging targets.
- Outbound connections from the router itself to attacker-controlled infrastructure, which would indicate post-exploitation code execution.
Detection Strategies
- Inspect web traffic destined for DIR-619L management interfaces for oversized POST bodies targeting /goform/ endpoints.
- Deploy network intrusion detection signatures matching the formAdvanceSetup URI combined with webpage= parameters longer than expected.
- Correlate router availability anomalies with HTTP request logs collected from upstream proxies or mirrored ports.
Monitoring Recommendations
- Forward router syslog output to a central log collector and alert on httpd segmentation faults or restart events.
- Monitor for new administrative sessions originating from unexpected source addresses or geolocations.
- Track DNS and outbound connection patterns from the router's WAN interface to identify command-and-control activity.
How to Mitigate CVE-2025-6617
Immediate Actions Required
- Disable remote (WAN-side) administration on all DIR-619L devices and restrict the management interface to a trusted management VLAN.
- Replace end-of-life DIR-619L hardware with a currently supported router that receives security updates.
- Rotate administrative credentials and disable unused services such as UPnP and remote management protocols.
Patch Information
No patch is available. D-Link has confirmed that the DIR-619L is no longer supported by the maintainer, and the vendor will not release fixed firmware for this model. The only durable remediation is hardware replacement. See the D-Link Official Website for current supported product lines.
Workarounds
- Place the router behind a separate firewall and block inbound HTTP/HTTPS access to its management interface from untrusted networks.
- Segment the device onto an isolated network with no access to sensitive internal systems until it is decommissioned.
- If continued use is unavoidable, restrict management access to a single hardened administrative workstation by source IP.
# Example iptables rule on an upstream firewall to block external access
# to the DIR-619L web management interface (replace 192.0.2.10 with the router IP)
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 80 -j DROP
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 443 -j DROP
# Allow only a designated admin workstation (replace 10.0.0.5)
iptables -I FORWARD -p tcp -s 10.0.0.5 -d 192.0.2.10 --dport 80 -j ACCEPT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
