CVE-2026-9295 Overview
CVE-2026-9295 is a buffer overflow vulnerability in the Edimax BR-6428NS wireless router running firmware version 1.10. The flaw resides in the formWirelessTbl function within /goform/formWirelessTbl, part of the device's POST request handler. Attackers can trigger the overflow by manipulating the vapurl argument in a crafted HTTP POST request. The exploit code is publicly available, and the vendor did not respond to disclosure attempts. The weakness is classified under CWE-119, improper restriction of operations within the bounds of a memory buffer.
Critical Impact
Remote attackers with low privileges can corrupt memory on affected Edimax BR-6428NS routers, potentially leading to denial of service or arbitrary code execution on the device.
Affected Products
- Edimax BR-6428NS firmware version 1.10
- Component: POST Request Handler (/goform/formWirelessTbl)
- Vulnerable function: formWirelessTbl
Discovery Timeline
- 2026-05-23 - CVE-2026-9295 published to NVD
- 2026-05-26 - Last updated in NVD database
Technical Details for CVE-2026-9295
Vulnerability Analysis
The vulnerability exists in the formWirelessTbl handler, which processes POST requests sent to /goform/formWirelessTbl on the router's web management interface. The handler reads the vapurl parameter from the request body and copies it into a fixed-size memory buffer without performing adequate length validation. Supplying an oversized vapurl value overflows the destination buffer and corrupts adjacent memory.
The attack is remotely reachable over the network and requires only low privileges, meaning an authenticated session to the device's web interface is sufficient. Successful exploitation can crash the HTTP server, force the device into a degraded state, or be weaponized to redirect execution flow on the MIPS-based firmware. Public exploit details are referenced in the Notion writeup and VulDB entry #365242.
Root Cause
The root cause is missing bounds checking on user-controlled input copied into a stack or static buffer. The vapurl argument is consumed by formWirelessTbl using an unsafe string copy operation, such as strcpy or sprintf, without enforcing a maximum length. This pattern is consistent with [CWE-119] and is common in embedded SOHO router firmware where input validation is delegated to assumed-trusted clients.
Attack Vector
An attacker on the same network, or one who has reached the management interface through misconfigured WAN exposure, sends a POST request to /goform/formWirelessTbl with an overlong vapurl value. Because the router does not validate length, the supplied string overruns the destination buffer. Crafting the payload with specific offsets can overwrite saved return addresses or function pointers on MIPS, enabling control of execution on the embedded device. No verified proof-of-concept code is reproduced here; refer to the VulDB submission #811534 for technical artifacts.
Detection Methods for CVE-2026-9295
Indicators of Compromise
- POST requests to /goform/formWirelessTbl containing unusually long vapurl parameter values, typically exceeding several hundred bytes.
- HTTP daemon crashes, watchdog reboots, or unexplained restarts of the router's management service.
- Outbound connections from the router to unfamiliar hosts following administrative login activity.
Detection Strategies
- Inspect HTTP request logs at network gateways and IDS sensors for POST traffic to /goform/formWirelessTbl with oversized form fields.
- Write Suricata or Snort signatures that flag vapurl= parameters exceeding a safe length threshold in HTTP POST bodies.
- Correlate router availability monitoring alerts with administrative web sessions to identify exploitation attempts.
Monitoring Recommendations
- Capture and centralize syslog output from the Edimax device, if exposed, to detect repeated crashes of the goform handler.
- Monitor authentication events on the router's web interface for brute-force activity that could precede exploitation.
- Alert on any new exposure of the router's management interface to untrusted networks or the public internet.
How to Mitigate CVE-2026-9295
Immediate Actions Required
- Restrict access to the router's web management interface to trusted management VLANs or specific administrative hosts.
- Disable remote WAN management on the BR-6428NS until a fixed firmware is available.
- Rotate administrative credentials and enforce strong, unique passwords to limit who can reach authenticated endpoints.
- Plan replacement of end-of-life Edimax BR-6428NS units, since the vendor did not respond to disclosure and no patch is announced.
Patch Information
No vendor patch is available at the time of publication. The vendor was contacted but did not respond to the disclosure, according to the VulDB advisory. Operators should track the Edimax support portal for firmware updates beyond version 1.10 and apply them once released.
Workarounds
- Place the router behind a perimeter firewall that blocks unsolicited inbound traffic to TCP/80 and TCP/443 of the device.
- Segment the wireless router from sensitive internal networks so that compromise does not yield lateral movement opportunities.
- Where feasible, replace the BR-6428NS with a currently supported device that receives security updates.
# Example: block external access to the router's web UI using iptables on an upstream gateway
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 80 -j DROP
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 443 -j DROP
# Allow only a trusted management host
iptables -I FORWARD -p tcp -s 10.10.10.5 -d 192.0.2.10 --dport 80 -j ACCEPT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
