CVE-2026-9462: Edimax EW-7438RPn Buffer Overflow Flaw

CVE-2026-9462 Overview

CVE-2026-9462 is a stack-based buffer overflow vulnerability in the Edimax EW-7438RPn wireless range extender running firmware version 1.31. The flaw resides in the formWpsProxyEnable function within the /goform/formWpsProxyEnable endpoint. Attackers can exploit the issue by manipulating the submit-url argument over the network. A public exploit is available, and the vendor did not respond to disclosure attempts. The vulnerability is classified 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 device's web management interface, potentially leading to arbitrary code execution or device compromise.

Affected Products

• Edimax EW-7438RPn firmware version 1.31
• The formWpsProxyEnable handler in /goform/formWpsProxyEnable
• Devices exposing the web management interface to untrusted networks

Discovery Timeline

• 2026-05-25 - CVE-2026-9462 published to NVD
• 2026-05-26 - Last updated in NVD database

Technical Details for CVE-2026-9462

Vulnerability Analysis

The vulnerability exists in the formWpsProxyEnable function exposed through the device's HTTP management interface at /goform/formWpsProxyEnable. The handler processes the submit-url POST parameter without validating its length before copying the data into a fixed-size stack buffer. Supplying an oversized value overflows the buffer and overwrites adjacent stack memory, including saved return addresses.

The Edimax EW-7438RPn is a consumer wireless range extender, and the web interface typically runs with elevated privileges on the embedded operating system. Successful exploitation can corrupt control flow within the web server process, enabling remote code execution on the device. The vendor was contacted but did not respond, and no patch has been published at the time of disclosure.

Root Cause

The root cause is unsafe handling of user-controlled input in formWpsProxyEnable. The submit-url argument is copied into a stack-allocated buffer without bounds checking, a classic [CWE-119] memory safety violation common in embedded MIPS and ARM web management binaries. Lack of stack canaries or address space layout randomization (ASLR) on many embedded targets makes exploitation reliable once the offset is known.

Attack Vector

The attack vector is network-based and requires low privileges. An authenticated attacker on the same network as the device, or one that can reach the web interface through misconfiguration or remote management exposure, can send a crafted HTTP request with an oversized submit-url parameter. The vulnerability mechanism is documented in the GitHub Vulnerability Documentation and the VulDB #365443 advisory.

No verified exploit code is reproduced here. Researchers should consult the public proof-of-concept linked above for technical details on offsets and payload construction.

Detection Methods for CVE-2026-9462

Indicators of Compromise

• HTTP POST requests to /goform/formWpsProxyEnable containing an unusually long submit-url parameter value
• Unexpected reboots, crashes, or service restarts of the web management daemon on the EW-7438RPn
• Outbound connections from the device to unfamiliar hosts after suspicious management interface activity

Detection Strategies

• Inspect HTTP traffic to embedded device management endpoints for parameter lengths exceeding typical bounds, particularly for /goform/ URIs
• Deploy network intrusion detection signatures that flag POST requests to formWpsProxyEnable with submit-url values longer than a few hundred bytes
• Correlate management interface access with device availability metrics to surface crash patterns indicative of exploitation attempts

Monitoring Recommendations

• Monitor administrative access logs on network gateways for repeated requests targeting Edimax /goform/ endpoints
• Track device uptime and reboot events for Edimax EW-7438RPn units, especially in environments where they have not been segmented
• Alert on any management interface access originating from non-administrative network segments or external networks

How to Mitigate CVE-2026-9462

Immediate Actions Required

• Restrict access to the EW-7438RPn web management interface to a dedicated administrative VLAN or trusted host
• Disable remote management features and confirm the device is not reachable from the internet or guest networks
• Inventory deployed Edimax EW-7438RPn devices and identify any units running firmware version 1.31
• Consider replacing the device if it has reached end-of-life or end-of-support status

Patch Information

No vendor patch is available. According to the public disclosure, the vendor was contacted before publication but did not respond. Refer to the VulDB #365443 entry and the VulDB CTI record for updates on remediation status.

Workarounds

• Place the device behind a firewall that blocks inbound HTTP and HTTPS traffic to the management interface from untrusted segments
• Enforce strong administrative credentials to reduce the likelihood of low-privileged attackers reaching the vulnerable endpoint
• Disable WPS-related features where possible to reduce the attack surface around the formWpsProxyEnable handler
• Plan migration to a supported wireless range extender from a vendor with an active security response program

# Example firewall rule restricting management access to a trusted subnet
iptables -A FORWARD -p tcp -d <device-ip> --dport 80 -s 10.10.10.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d <device-ip> --dport 80 -j DROP