CVE-2026-9360: Edimax EW-7438RPn Buffer Overflow Flaw

CVE-2026-9360 Overview

CVE-2026-9360 is a buffer overflow vulnerability in the Edimax EW-7438RPn Wi-Fi range extender running firmware version 1.28a. The flaw resides in the formwlencrypt24g function within /goform/formwlencrypt24g, which handles POST requests submitted to the device's web interface. Manipulation of the key1 argument triggers memory corruption in the request handler. Attackers can exploit the issue remotely over the network with low-privilege credentials. The exploit has been publicly released, increasing the risk of opportunistic attacks against exposed devices. The vendor was contacted prior to disclosure but did not respond.

Critical Impact
Remote attackers with low privileges can trigger memory corruption in the device's HTTP server, leading to potential code execution or denial of service on affected Edimax EW-7438RPn extenders.

Affected Products

Edimax EW-7438RPn Mini range extender
Firmware version 1.28a
/goform/formwlencrypt24g POST request handler

Discovery Timeline

2026-05-24 - CVE-2026-9360 published to the National Vulnerability Database
2026-05-26 - Last updated in NVD database

Technical Details for CVE-2026-9360

Vulnerability Analysis

The vulnerability is classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer). The defect exists in the formwlencrypt24g handler used to configure 2.4 GHz wireless encryption settings on the Edimax EW-7438RPn. When the device processes a POST request to /goform/formwlencrypt24g, the handler reads the key1 parameter without validating its length before copying it into a fixed-size buffer. An attacker who supplies an oversized key1 value overflows the destination buffer, corrupting adjacent memory inside the embedded HTTP server process.

Root Cause

The root cause is missing bounds checking on the key1 POST parameter inside formwlencrypt24g. The handler trusts user-supplied input from the wireless encryption configuration form and copies it directly into a stack or heap buffer. Embedded devices like the EW-7438RPn typically lack modern exploit mitigations such as Address Space Layout Randomization (ASLR) and stack canaries, which amplifies the impact of the overflow.

Attack Vector

The attack is launched remotely over the network. The vector requires low-privilege authentication to the device's web administration interface. Once authenticated, an attacker submits a crafted POST request with an oversized key1 value to /goform/formwlencrypt24g. The resulting memory corruption can cause the HTTP service to crash or, depending on memory layout, redirect execution flow. Publicly available exploit code lowers the barrier for attackers targeting exposed extenders.

No verified exploit code is reproduced here. Technical details of the parameter manipulation are documented in the Notion writeup on the EDIMAX device and the VulDB entry #365323.

Detection Methods for CVE-2026-9360

Indicators of Compromise

Unexpected reboots or crashes of the Edimax EW-7438RPn HTTP service following POST requests to /goform/formwlencrypt24g.
HTTP POST bodies targeting the formwlencrypt24g endpoint containing abnormally long key1 values.
Unauthenticated or unexpected administrative sessions originating from external IP addresses against the extender's management interface.

Detection Strategies

Inspect HTTP traffic to and from the device for requests to /goform/formwlencrypt24g and measure the length of the key1 parameter against a baseline.
Deploy network signatures that flag POST requests to formwlencrypt24g with parameter values exceeding expected WPA/WEP key lengths.
Correlate device reboot events, syslog crashes, or watchdog resets with preceding HTTP POST activity from the same source.

Monitoring Recommendations

Log all authentication attempts and configuration changes on the Edimax management interface.
Forward router and extender syslogs to a centralized logging platform for analysis and historical correlation.
Restrict and monitor inbound access to TCP ports hosting the device's web administration service.

How to Mitigate CVE-2026-9360

Immediate Actions Required

Remove the Edimax EW-7438RPn management interface from any network segment reachable by untrusted users or the internet.
Change default and shared administrative credentials to strong, unique passwords to raise the bar for the low-privilege authentication required for exploitation.
Inventory deployed EW-7438RPn devices running firmware 1.28a and prioritize replacement or isolation.

Patch Information

No vendor patch is currently available. According to the disclosure, Edimax was contacted prior to public release but did not respond. Customers should monitor the Edimax support site for any future firmware update addressing CVE-2026-9360 and consult the VulDB advisory #365323 for tracking updates.

Workarounds

Place the extender on an isolated VLAN with no routing to the internet or sensitive internal networks.
Disable remote administration and restrict the web interface to a single trusted management host.
Consider replacing end-of-support or unresponsive-vendor devices with hardware that receives active security maintenance.

bash

# Example: restrict access to the extender management interface using iptables on an upstream gateway
# Replace EXTENDER_IP and MGMT_HOST with your environment values
iptables -A FORWARD -p tcp -d EXTENDER_IP --dport 80 -s MGMT_HOST -j ACCEPT
iptables -A FORWARD -p tcp -d EXTENDER_IP --dport 80 -j DROP
iptables -A FORWARD -p tcp -d EXTENDER_IP --dport 443 -s MGMT_HOST -j ACCEPT
iptables -A FORWARD -p tcp -d EXTENDER_IP --dport 443 -j DROP