CVE-2025-2551 Overview
CVE-2025-2551 is an improper access control vulnerability [CWE-266] affecting D-Link DIR-618 and DIR-605L routers running firmware versions 2.02 and 3.02 respectively. The flaw resides in the /goform/formSetPortTr endpoint. An attacker with access to the local network can manipulate the endpoint to bypass access controls and modify port trigger configurations. The exploit details have been publicly disclosed. Both affected devices are end-of-life and no longer receive security updates from D-Link.
Critical Impact
An adjacent-network attacker can abuse /goform/formSetPortTr to alter router configuration without proper authorization, and no vendor patch is available because the affected devices are end-of-life.
Affected Products
- D-Link DIR-618 firmware version 2.02
- D-Link DIR-605L firmware version 3.02
- Both models are no longer supported by the vendor
Discovery Timeline
- 2025-03-20 - CVE-2025-2551 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-2551
Vulnerability Analysis
The vulnerability affects the formSetPortTr handler exposed under the router's /goform/ HTTP interface. This endpoint controls port triggering configuration on the device. The handler fails to enforce proper access controls before processing incoming requests. An attacker on the same local network segment can send crafted HTTP requests to modify port trigger rules without holding the required privileges.
The flaw is classified under CWE-266 (Incorrect Privilege Assignment), indicating that the endpoint grants operational access beyond what its role should permit. Because these devices sit at the network edge, unauthorized modification of port triggers can expose internal services or redirect traffic in unintended ways.
Root Cause
The root cause is missing or insufficient authorization checks in the formSetPortTr request handler. The web management interface accepts configuration changes on this endpoint without verifying that the requester holds administrative privileges. This design flaw is common in legacy small office and home office (SOHO) router firmware where administrative endpoints rely on session context that is not consistently enforced.
Attack Vector
Exploitation requires adjacent network access, meaning the attacker must be on the same local network as the target router. This can be achieved through a compromised device on the LAN, a rogue wireless client, or a hostile insider. Once connected, the attacker issues HTTP requests directly to /goform/formSetPortTr to alter port triggering rules. No prior authentication and no user interaction are required. Refer to the VulDB entry #300165 and the technical write-ups for DIR-605L and DIR-618 for endpoint-level analysis.
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Stop Identity AttacksDetection Methods for CVE-2025-2551
Indicators of Compromise
- Unexpected HTTP POST requests to /goform/formSetPortTr originating from LAN clients
- Unauthorized changes to port triggering rules in the router configuration
- New or modified port forwarding entries that do not match administrator activity
- Presence of end-of-life D-Link DIR-618 or DIR-605L devices in the network inventory
Detection Strategies
- Monitor internal HTTP traffic destined for router management interfaces on the LAN
- Alert on requests to /goform/ endpoints from non-administrator endpoints
- Baseline router configuration and detect deviations in port triggering or forwarding tables
- Correlate device inventory data to identify unsupported D-Link models still in use
Monitoring Recommendations
- Enable logging on network segmentation devices to capture LAN-side HTTP flows to the router
- Periodically export router configuration and diff against a trusted baseline
- Watch for lateral movement behaviors originating from LAN hosts targeting gateway IPs
- Track SOHO firmware versions using asset management to flag out-of-support devices
How to Mitigate CVE-2025-2551
Immediate Actions Required
- Replace affected DIR-618 and DIR-605L devices with vendor-supported hardware
- Restrict access to the router management interface to a dedicated administrative VLAN
- Disable remote and untrusted-client access to the web administration interface
- Segment untrusted wireless and guest networks away from the router LAN interface
Patch Information
No vendor patch is available. D-Link has designated the DIR-618 and DIR-605L as end-of-life, and the vendor will not release security updates for these models. Refer to the D-Link official website for current supported product lines and replace affected units accordingly.
Workarounds
- Block LAN client access to /goform/formSetPortTr using an upstream firewall or network access control policy
- Enforce network segmentation so only trusted administrative hosts can reach the router web interface
- Disable port triggering functionality if not required by the environment
- Migrate to a supported router platform that receives active security maintenance
# Example: restrict router management access to a single admin host via iptables on an upstream gateway
iptables -A FORWARD -s 192.168.1.10 -d 192.168.1.1 -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
