CVE-2026-9346 Overview
CVE-2026-9346 is a buffer overflow vulnerability in the Edimax EW-7438RPn wireless range extender through firmware version 1.31. The flaw resides in the formWirelessTbl function within /goform/formWirelessTbl, part of the device's webs web management component. Attackers can trigger the overflow by manipulating the submit-url argument. The issue is classified as CWE-119 — improper restriction of operations within the bounds of a memory buffer. A public exploit has been disclosed, and the vendor did not respond to disclosure attempts, leaving affected devices without an official patch.
Critical Impact
Remote attackers with low privileges can corrupt memory on the device, potentially achieving arbitrary code execution on the embedded web server and full compromise of the range extender.
Affected Products
- Edimax EW-7438RPn firmware up to and including version 1.31
- The formWirelessTbl handler in the /goform/formWirelessTbl endpoint
- The webs HTTP management component
Discovery Timeline
- 2026-05-24 - CVE-2026-9346 published to NVD
- 2026-05-26 - Last updated in NVD database
Technical Details for CVE-2026-9346
Vulnerability Analysis
The vulnerability exists in the formWirelessTbl request handler exposed at /goform/formWirelessTbl by the embedded webs HTTP server on the Edimax EW-7438RPn. The handler reads the submit-url parameter from the incoming HTTP request and copies it into a fixed-size stack buffer without enforcing a length boundary. Supplying an oversized value overruns the destination buffer, corrupting adjacent stack data including the saved return address. The flaw is exploitable over the network and requires only low-level authentication, in line with the published CVSS v4.0 vector indicating network reachability and low attack complexity.
Root Cause
The root cause is classified under CWE-119: improper restriction of operations within the bounds of a memory buffer. The formWirelessTbl function performs an unbounded copy of attacker-controlled input from the submit-url HTTP argument into a fixed-size stack buffer. No length validation is performed before the copy.
Attack Vector
An authenticated attacker on the network sends a crafted HTTP POST request to /goform/formWirelessTbl with an oversized submit-url parameter. The malformed value overflows the stack buffer in the webs process, enabling memory corruption and potential control of execution flow on the MIPS-based device. Public proof-of-concept material has been released through the GitHub vulnerability writeup and tracked in VulDB entry #365309.
No verified code example is available. See the GitHub disclosure for the technical proof-of-concept details.
Detection Methods for CVE-2026-9346
Indicators of Compromise
- HTTP POST requests targeting /goform/formWirelessTbl containing abnormally long submit-url parameter values.
- Unexpected crashes, reboots, or restarts of the webs process on the EW-7438RPn.
- Outbound connections initiated by the device to unknown external hosts following management interface access.
Detection Strategies
- Inspect web access logs and network traffic for submit-url arguments exceeding expected length thresholds on /goform/formWirelessTbl.
- Deploy network IDS signatures that flag oversized form-field payloads in HTTP requests to Edimax administrative endpoints.
- Correlate authentication events to the device admin interface with subsequent anomalous device behavior.
Monitoring Recommendations
- Restrict and monitor management plane access to the EW-7438RPn from segmented administrative VLANs only.
- Capture and retain HTTP request logs from any reverse proxy fronting embedded network devices for forensic review.
- Alert on repeated failed administrative authentication attempts that precede malformed /goform/* requests.
How to Mitigate CVE-2026-9346
Immediate Actions Required
- Remove the EW-7438RPn from any internet-exposed network segment and block external access to its management interface.
- Disable remote administration features and enforce strong, unique credentials for the local admin account.
- Inventory all deployed Edimax EW-7438RPn devices on firmware 1.31 or earlier and plan for replacement.
Patch Information
No vendor patch is available. According to the disclosure, the vendor was contacted early but did not respond. Organizations should treat the device as end-of-support for security purposes and plan migration to a supported wireless extender. Track updates via VulDB #365309 and the CTI report.
Workarounds
- Place the device behind a firewall that restricts inbound HTTP/HTTPS to the management interface to trusted internal hosts only.
- Segment IoT and consumer-grade network hardware onto isolated VLANs without routing to corporate or sensitive resources.
- Replace the affected device with a vendor-supported model that receives active firmware updates.
# Example: restrict management interface access to a trusted admin host
iptables -A FORWARD -p tcp -d <edimax_device_ip> --dport 80 -s <admin_workstation_ip> -j ACCEPT
iptables -A FORWARD -p tcp -d <edimax_device_ip> --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
