CVE-2025-6114 Overview
CVE-2025-6114 is a stack-based buffer overflow in the D-Link DIR-619L router running firmware version 2.06B01. The flaw resides in the form_portforwarding function handling requests to /goform/form_portforwarding. Attackers manipulate the ingress_name_%d, sched_name_%d, and name_%d arguments to corrupt stack memory. The exploit has been publicly disclosed, and the affected device is end-of-life with no vendor patch planned. The vulnerability is tracked under [CWE-119] and affects products D-Link no longer supports.
Critical Impact
Remote attackers with low privileges can trigger memory corruption in form_portforwarding, potentially leading to arbitrary code execution on unsupported D-Link DIR-619L devices.
Affected Products
- D-Link DIR-619L hardware
- D-Link DIR-619L firmware version 2.06B01
- End-of-life D-Link DIR-619L deployments (no vendor support)
Discovery Timeline
- 2025-06-16 - CVE-2025-6114 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-6114
Vulnerability Analysis
The vulnerability is a stack-based buffer overflow in the form_portforwarding handler of the D-Link DIR-619L web administration interface. The function processes HTTP POST requests submitted to /goform/form_portforwarding and reads attacker-controlled values for the indexed arguments ingress_name_%d, sched_name_%d, and name_%d. These parameters are copied into fixed-size stack buffers without proper length validation. Oversized values overwrite adjacent stack memory, including saved return addresses on the MIPS-based device. Successful exploitation can corrupt control flow and lead to arbitrary code execution in the context of the router's web service. The router runs the affected service with elevated privileges, so a compromise grants full control over the device, its routing tables, DNS settings, and traffic.
Root Cause
The root cause is missing bounds checking on user-supplied form field data within form_portforwarding. The function trusts the length of values passed through repeated indexed parameters and uses unsafe string copy operations into stack-allocated buffers, matching the [CWE-119] pattern of improper restriction of operations within the bounds of a memory buffer.
Attack Vector
The attack is network-based and requires only low privileges on the device's management interface. An attacker reachable over the LAN, or over the WAN where remote administration is enabled, sends a crafted HTTP request to /goform/form_portforwarding with overlong ingress_name_%d, sched_name_%d, or name_%d parameter values. A public proof-of-concept has been documented in the GitHub PoC for Vulnerability and additional details are available in VulDB #312583.
// No verified exploit code is reproduced here.
// Refer to the published proof-of-concept for technical details.
Detection Methods for CVE-2025-6114
Indicators of Compromise
- HTTP POST requests to /goform/form_portforwarding containing unusually long ingress_name_*, sched_name_*, or name_* parameter values.
- Web administration service crashes, reboots, or watchdog resets on DIR-619L devices following inbound HTTP traffic.
- Unexpected port forwarding, DNS, or firewall rule changes on affected routers.
Detection Strategies
- Inspect HTTP request bodies destined for the router's management interface and flag parameter values that exceed expected lengths for port forwarding fields.
- Deploy network intrusion detection signatures that match POST requests to /goform/form_portforwarding with abnormally long indexed name arguments.
- Correlate router availability monitoring with management-plane HTTP logs to detect crash-restart cycles indicative of exploitation attempts.
Monitoring Recommendations
- Continuously monitor administrative access to DIR-619L web interfaces and alert on requests originating from untrusted networks.
- Forward router syslog and HTTP access logs to a central log platform for retention and anomaly analysis.
- Track outbound connections from the router to non-corporate destinations, which may indicate post-exploitation activity.
How to Mitigate CVE-2025-6114
Immediate Actions Required
- Disable remote (WAN-side) HTTP administration on all DIR-619L devices.
- Restrict LAN access to the router's management interface to a dedicated administrative VLAN or host.
- Inventory the network for DIR-619L hardware running firmware 2.06B01 and plan replacement with a supported model.
Patch Information
D-Link has confirmed that the DIR-619L is end-of-life and no longer supported by the maintainer. No security patch will be released for CVE-2025-6114. Refer to the D-Link Official Website for current supported models and end-of-life notices. Affected organizations should treat decommissioning as the primary remediation.
Workarounds
- Replace DIR-619L devices with a vendor-supported router that receives security updates.
- If immediate replacement is not possible, isolate the device behind an upstream firewall and block all untrusted access to TCP/80 and TCP/443 on the router's interfaces.
- Disable port forwarding configuration features that route through form_portforwarding until the device is retired.
# Example: block external access to the router management interface upstream
iptables -A FORWARD -d <router_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router_ip> -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
