CVE-2026-9344: Edimax EW-7438RPn Buffer Overflow Flaw

CVE-2026-9344 Overview

CVE-2026-9344 is a stack-based buffer overflow vulnerability affecting the Edimax EW-7438RPn wireless range extender through version 1.31. The flaw resides in an unknown function within /goform/formWpsStart, part of the device's webs web server component. Attackers can trigger the overflow by manipulating the pinCode or wlan-url arguments. The vulnerability is remotely exploitable and a public disclosure of the exploit exists. The vendor was contacted prior to disclosure but did not respond, leaving deployed devices without an official patch.

Critical Impact
Remote attackers with low-level privileges can corrupt the stack on affected Edimax EW-7438RPn devices, enabling potential code execution and full compromise of the network extender.

Affected Products

Edimax EW-7438RPn firmware versions up to and including 1.31
The vulnerable webs HTTP server component
The /goform/formWpsStart WPS configuration handler

Discovery Timeline

2026-05-24 - CVE-2026-9344 published to NVD
2026-05-26 - Last updated in NVD database

Technical Details for CVE-2026-9344

Vulnerability Analysis

The vulnerability is classified under [CWE-119] as an improper restriction of operations within the bounds of a memory buffer. The flawed code path in /goform/formWpsStart accepts attacker-controlled input through the pinCode and wlan-url HTTP parameters and copies that data onto a fixed-size stack buffer without enforcing a length check. When the supplied input exceeds the buffer size, the overflow overwrites adjacent stack memory, including saved return addresses and frame pointers.

Because the webs daemon on the EW-7438RPn typically runs with elevated privileges on the embedded Linux system, successful exploitation can yield arbitrary code execution at the device's privilege level. The attack requires network reachability to the device's web interface and at least low-level authentication context.

The EPSS score is 0.041% (12.82 percentile), reflecting limited observed exploitation activity, though public exploit material increases the likelihood of opportunistic targeting.

Root Cause

The root cause is the absence of bounds checking when the formWpsStart handler processes WPS-related parameters. The handler writes user-supplied pinCode and wlan-url values into stack-allocated buffers using unsafe string operations. Embedded vendors frequently rely on functions like strcpy or sprintf in goform handlers, which do not validate destination buffer size.

Attack Vector

An attacker reachable over the network sends a crafted HTTP request to /goform/formWpsStart with an oversized pinCode or wlan-url parameter. The malformed request triggers the stack overflow inside the webs process. On MIPS or ARM embedded targets typical of this device class, an attacker can overwrite the return address to redirect execution into shellcode or a ROP chain, ultimately gaining a foothold on the device.

The vulnerability mechanism is documented in the GitHub vulnerability writeup and the VulDB advisory #365307. No verified code examples are reproduced here; consult the linked references for technical details.

Detection Methods for CVE-2026-9344

Indicators of Compromise

HTTP POST or GET requests to /goform/formWpsStart containing abnormally long pinCode or wlan-url parameter values
Crashes or unexpected restarts of the webs process on the Edimax EW-7438RPn
Outbound connections from the extender to unknown hosts following inbound WPS-related requests
New or modified configuration entries on the device that were not initiated by an administrator

Detection Strategies

Inspect web server access logs for requests to /goform/formWpsStart with parameter lengths exceeding expected WPS PIN formats (typically 8 digits)
Deploy network intrusion detection signatures that flag oversized parameter values in HTTP requests targeting embedded device management interfaces
Correlate device reboot events with preceding HTTP traffic patterns to identify potential exploitation attempts

Monitoring Recommendations

Capture and retain HTTP request logs from network range extenders for forensic review
Monitor SNMP or syslog output from affected devices for service crashes or anomalous behavior
Alert on any administrative interface access from non-management network segments

How to Mitigate CVE-2026-9344

Immediate Actions Required

Restrict access to the device's web management interface using network segmentation and firewall rules, permitting only trusted administrative hosts
Disable WPS functionality on the Edimax EW-7438RPn if the feature is not required for operations
Replace affected devices with supported hardware where feasible, given the vendor's lack of response to the disclosure

Patch Information

No official patch is available. The vendor was contacted prior to disclosure but did not respond. Organizations operating affected devices should treat the vulnerability as unpatched and plan compensating controls or device replacement. Monitor the VulDB entry #365307 for any future vendor updates.

Workarounds

Block external access to TCP ports 80 and 443 on the device at the network boundary
Place the extender on an isolated VLAN with strict egress filtering to limit post-exploitation movement
Rotate any administrative credentials used on the device and disable unused services exposed by the webs daemon
Schedule periodic reviews of the GitHub vulnerability document for any community-supplied mitigations

bash

# Example iptables rule restricting web UI access to a single management host
iptables -A INPUT -p tcp --dport 80 -s 192.0.2.10 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.0.2.10 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP