CVE-2026-7683 Overview
CVE-2026-7683 is a command injection vulnerability affecting the Edimax BR-6428nC wireless router up to firmware version 1.16. The flaw resides in an unknown function of the /goform/setWAN endpoint within the device Web Interface. Attackers can manipulate the pppUserName or pptpUserName parameters to inject operating system commands. The attack is remotely exploitable and a public exploit has been disclosed. According to VulDB, the vendor was contacted before disclosure but did not respond. The weakness is classified under [CWE-74] (Improper Neutralization of Special Elements in Output Used by a Downstream Component).
Critical Impact
Authenticated remote attackers can inject arbitrary OS commands through WAN configuration parameters, leading to potential takeover of the affected router.
Affected Products
- Edimax BR-6428nC firmware versions up to and including 1.16
- /goform/setWAN Web Interface endpoint
- pppUserName and pptpUserName request parameters
Discovery Timeline
- 2026-05-03 - CVE-2026-7683 published to NVD
- 2026-05-05 - Last updated in NVD database
Technical Details for CVE-2026-7683
Vulnerability Analysis
The vulnerability exists in the WAN configuration handler exposed through /goform/setWAN on the Edimax BR-6428nC router. When a user submits PPP or PPTP credentials, the firmware passes the pppUserName and pptpUserName values to a downstream system call without proper neutralization of shell metacharacters. Attackers can append shell operators such as ;, |, or backticks to inject additional commands. The injected payload executes in the context of the router's web service, which typically runs with elevated privileges on embedded Linux devices. Successful exploitation yields command execution on the device, enabling configuration tampering, credential theft, traffic interception, and persistence within the home or small office network.
Root Cause
The root cause is improper neutralization of special elements in user-supplied input passed to a downstream OS command interpreter [CWE-74]. The firmware concatenates the pppUserName and pptpUserName values directly into a command string without escaping or validating against an allow-list of permitted characters.
Attack Vector
The attack vector is network-based and requires low privileges on the router's Web Interface. An attacker submits a crafted POST request to /goform/setWAN containing shell metacharacters in the pppUserName or pptpUserName fields. The EPSS score is 0.924% (76th percentile), reflecting moderate exploitation likelihood.
No verified exploit code is reproduced here. Technical details are documented in the public Notion report on pppUserName injection and the Notion report on pptpUserName injection.
Detection Methods for CVE-2026-7683
Indicators of Compromise
- HTTP POST requests to /goform/setWAN containing shell metacharacters such as ;, |, &, $(), or backticks within pppUserName or pptpUserName parameters
- Unexpected outbound connections originating from the router management interface
- Modifications to WAN, DNS, or DHCP configuration that were not initiated by an administrator
Detection Strategies
- Inspect web server and router logs for malformed credential strings submitted to /goform/setWAN
- Deploy network IDS rules that flag shell metacharacter sequences in HTTP form bodies destined for the router management interface
- Monitor for new processes spawned by the router's HTTP daemon that deviate from baseline behavior
Monitoring Recommendations
- Capture and review router administrative HTTP traffic, especially from non-administrative source addresses
- Alert on configuration changes to PPP and PPTP WAN settings outside scheduled maintenance windows
- Track DNS query patterns from the router itself for signs of beaconing or data exfiltration
How to Mitigate CVE-2026-7683
Immediate Actions Required
- Restrict access to the router Web Interface to trusted management VLANs and disable remote WAN-side administration
- Change default and weak administrative credentials on the BR-6428nC to reduce exposure to authenticated attackers
- Audit current WAN PPP and PPTP configurations for suspicious values and reset them to known-good state
Patch Information
No vendor patch is available. According to the VulDB record, Edimax was contacted prior to public disclosure but did not respond. Affected organizations should plan to replace the BR-6428nC with a supported device that receives active firmware updates. See VulDB entry #360842 for ongoing tracking.
Workarounds
- Place the router behind a network segmentation boundary that blocks untrusted hosts from reaching the management interface
- Disable the PPP and PPTP WAN modes if alternative connection types such as DHCP or static IP are usable
- Replace end-of-life BR-6428nC hardware with a current-generation router that receives security updates
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
