CVE-2025-7945 Overview
CVE-2025-7945 is a buffer overflow vulnerability in the D-Link DIR-513 router firmware up to version 20190831. The flaw resides in the formSetWanDhcpplus function within /goform/formSetWanDhcpplus, where the curTime argument is processed without proper bounds checking [CWE-119]. Remote attackers can trigger the overflow over the network with low privileges, potentially leading to memory corruption and code execution on the device. D-Link DIR-513 is an end-of-life product and the vendor no longer provides security maintenance, meaning no official patch will be released. A public proof-of-concept exists, increasing the likelihood of opportunistic exploitation against exposed devices.
Critical Impact
Remote attackers can corrupt memory in the router's web management handler, enabling potential code execution against an unsupported device with no vendor patch path.
Affected Products
- D-Link DIR-513 router (firmware up to 20190831)
- /goform/formSetWanDhcpplus web management endpoint
- End-of-life D-Link consumer routers no longer receiving security updates
Discovery Timeline
- 2025-07-22 - CVE-2025-7945 published to NVD
- 2026-04-15 - Last updated in NVD database
Technical Details for CVE-2025-7945
Vulnerability Analysis
The vulnerability exists in the formSetWanDhcpplus handler exposed through the router's web administration interface at /goform/formSetWanDhcpplus. The handler accepts a curTime parameter from HTTP requests and copies the attacker-supplied value into a fixed-size stack buffer without validating the input length. When the supplied curTime value exceeds the buffer capacity, adjacent stack memory is overwritten, including saved return addresses and local variables. On MIPS-based D-Link consumer routers, this class of overflow is commonly leveraged to redirect execution flow and achieve arbitrary code execution under the privileges of the embedded web server, which typically runs as root.
Root Cause
The root cause is a classic memory buffer mismanagement issue tracked under [CWE-119]. The formSetWanDhcpplus function fails to enforce length checks on the curTime argument before copying it into a fixed-length buffer. No sanitization, bounds validation, or safer string-handling primitives are applied prior to the copy, allowing an attacker to overflow the destination buffer with controlled data.
Attack Vector
The attack is performed over the network against the router's HTTP management interface. An attacker who can reach the management endpoint, either on the LAN or through a misconfigured WAN-side management exposure, can submit a crafted POST request to /goform/formSetWanDhcpplus containing an oversized curTime parameter. The CVSS v4.0 vector indicates that low privileges are required, suggesting the endpoint expects an authenticated session, though weak or default credentials on consumer routers reduce this barrier in practice. Successful exploitation can compromise confidentiality, integrity, and availability of the device. A public proof-of-concept is hosted on the GitHub PoC Repository.
No verified exploit code is reproduced here. Refer to the VulDB entry #317086 for additional technical context.
Detection Methods for CVE-2025-7945
Indicators of Compromise
- HTTP POST requests to /goform/formSetWanDhcpplus containing unusually long curTime parameter values.
- Unexpected reboots, crashes, or instability of the DIR-513 web administration interface.
- Outbound connections from the router to unfamiliar hosts following inbound management traffic.
- New or unexpected configuration changes to WAN or DHCP settings on the device.
Detection Strategies
- Inspect network traffic for HTTP requests targeting /goform/formSetWanDhcpplus and flag payloads where curTime exceeds expected length boundaries.
- Deploy IDS/IPS signatures that match oversized parameter values in form submissions to D-Link goform endpoints.
- Correlate router management traffic with subsequent anomalous outbound behavior from the same device.
Monitoring Recommendations
- Restrict and monitor any device with management interfaces reachable from untrusted segments.
- Log all administrative HTTP access to consumer routers and alert on requests to known vulnerable form handlers.
- Track end-of-life network appliances in asset inventory and prioritize them for monitoring or replacement.
How to Mitigate CVE-2025-7945
Immediate Actions Required
- Replace the D-Link DIR-513 with a vendor-supported router, as the device is end-of-life and will not receive a security patch.
- Disable remote (WAN-side) administration on the router until decommissioning is complete.
- Restrict access to the LAN-side management interface to a dedicated administrative VLAN or trusted host.
- Change default and weak credentials on the router to limit access to authenticated attackers.
Patch Information
No patch is available. The vendor advisory at the D-Link Official Website confirms the DIR-513 is outside the supported product lifecycle. Mitigation is limited to compensating controls and device replacement.
Workarounds
- Place the affected router behind an upstream firewall that blocks inbound access to its management interface.
- Segment the router onto an isolated network where it cannot reach sensitive internal resources.
- Block external access to TCP port 80 and 443 on the device at the network perimeter.
- Decommission the device on a defined timeline and migrate to a currently supported platform.
# Example: block external access to the router's HTTP management interface
iptables -A INPUT -i wan0 -p tcp --dport 80 -j DROP
iptables -A INPUT -i wan0 -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.
