CVE-2025-70226: D-Link DIR-513 Buffer Overflow Flaw

CVE-2025-70226 Overview

CVE-2025-70226 is a stack buffer overflow vulnerability in the D-Link DIR-513 wireless router running firmware version 1.10. The flaw resides in the goform/formEasySetupWizard endpoint, where the curTime parameter is copied into a fixed-size stack buffer without proper bounds checking. An unauthenticated remote attacker can send a crafted HTTP request to trigger memory corruption and execute arbitrary code on the device. The weakness is classified as [CWE-121] Stack-based Buffer Overflow.

Critical Impact
Unauthenticated remote attackers can overwrite the stack via the curTime HTTP parameter, achieving arbitrary code execution on affected D-Link DIR-513 routers exposed to the network.

Affected Products

D-Link DIR-513 router (hardware)
D-Link DIR-513 firmware version 1.10
Network deployments exposing goform/formEasySetupWizard to untrusted networks

Discovery Timeline

2026-03-04 - CVE-2025-70226 published to NVD
2026-03-06 - Last updated in NVD database

Technical Details for CVE-2025-70226

Vulnerability Analysis

The DIR-513 web management interface exposes the formEasySetupWizard handler under the goform path. The handler reads the curTime HTTP parameter and copies the supplied value into a fixed-size buffer allocated on the stack. No length validation is performed before the copy operation. When an attacker supplies a value longer than the destination buffer, adjacent stack memory is overwritten, including the saved return address.

Because the affected request is processed by the device web server before authentication on the setup wizard endpoint, exploitation requires only network reachability. The router runs on embedded MIPS or ARM firmware without modern exploit mitigations such as stack canaries or address space layout randomization, which simplifies reliable code execution. Successful exploitation grants the attacker control of the HTTP daemon process, typically running with root privileges on consumer-grade D-Link devices.

Root Cause

The root cause is missing input validation on the curTime parameter inside the formEasySetupWizard form handler. The handler uses an unbounded string copy primitive that writes user-controlled bytes to a fixed-length stack buffer. This pattern matches [CWE-121] and is a recurring class of defect in legacy SOHO router firmware that lacks modern compiler hardening.

Attack Vector

An attacker sends an HTTP POST request to goform/formEasySetupWizard with an oversized curTime parameter. The request can originate from any host with network access to the router's web interface, including the local LAN, the WAN if remote management is enabled, or a malicious page exploiting DNS rebinding. No credentials or user interaction are required. After overflowing the stack frame, the attacker redirects execution to attacker-controlled data, executing shellcode that yields a root shell on the device.

No verified public exploit code is available at this time. Refer to the GitHub CVE Repository for technical analysis as it becomes available.

Detection Methods for CVE-2025-70226

Indicators of Compromise

HTTP POST requests to /goform/formEasySetupWizard containing unusually long curTime parameter values
Web server process crashes or unexpected reboots on the DIR-513 router
Outbound connections from the router to unknown external hosts following inbound HTTP traffic to the management interface
New or unexpected processes listening on non-standard ports on the device

Detection Strategies

Inspect network traffic for HTTP requests targeting formEasySetupWizard with parameter lengths exceeding typical timestamp values
Apply IDS or IPS signatures that flag oversized form parameters submitted to D-Link goform endpoints
Monitor router syslog output for HTTP daemon crashes, segmentation faults, or watchdog-triggered restarts
Correlate inbound scans on TCP ports 80 and 443 against IoT subnets containing D-Link devices

Monitoring Recommendations

Forward router logs to a central log collector and alert on repeated HTTP 5xx responses from the management interface
Track router uptime and flag unexpected reboot patterns that may indicate exploitation attempts
Enumerate the network for DIR-513 devices and confirm firmware version 1.10 exposure on management ports

How to Mitigate CVE-2025-70226

Immediate Actions Required

Restrict access to the router web management interface to trusted internal hosts only, and disable WAN-side remote management
Place the DIR-513 behind a segmentation boundary that blocks untrusted clients from reaching goform endpoints
Inventory all DIR-513 devices and confirm firmware version; plan replacement if the model is end-of-life
Monitor the D-Link Security Bulletin for vendor guidance on this CVE

Patch Information

At the time of NVD publication, no fixed firmware version has been associated with CVE-2025-70226. The DIR-513 is a legacy model and may not receive a security update. Consult the D-Link Product Information page and the D-Link Security Bulletin for the latest vendor advisories. If no patch is released, replace the device with a currently supported model.

Workarounds

Disable remote administration over the WAN interface in the router configuration
Block inbound traffic to TCP ports 80 and 443 on the router from untrusted networks at an upstream firewall
Place the device on an isolated VLAN with strict ACLs limiting which clients can reach the management interface
Replace the DIR-513 with a vendor-supported router that receives current security updates

bash

# Example upstream firewall rule to block external access to the router admin interface
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -j DROP