CVE-2026-90706 Overview
CVE-2026-90706 is an operating system command injection vulnerability [CWE-77] in the D-Link DWR-M921 router firmware version 1.1.52. The flaw resides in the formWsc function within /boafrm/formWsc. Attackers can manipulate the targetAPSsid parameter to inject arbitrary operating system commands. Exploitation requires network access and high privileges on the device. A public proof-of-concept exists, increasing the likelihood of opportunistic exploitation against exposed devices.
Critical Impact
Authenticated remote attackers can inject operating system commands through the targetAPSsid parameter of /boafrm/formWsc, gaining command execution on affected D-Link DWR-M921 routers running firmware 1.1.52.
Affected Products
- D-Link DWR-M921 router
- Firmware version 1.1.52
- formWsc handler in /boafrm/formWsc
Discovery Timeline
- 2026-09-14 - CVE-2026-90706 published to the National Vulnerability Database (NVD)
- 2026-09-14 - Last updated in NVD database
Technical Details for CVE-2026-90706
Vulnerability Analysis
The vulnerability affects the formWsc function that services requests to the /boafrm/formWsc endpoint on the D-Link DWR-M921 router. The handler accepts a targetAPSsid parameter tied to Wi-Fi Protected Setup (WPS) configuration. User-supplied input from this parameter is passed to an operating system command execution routine without adequate sanitization or neutralization of shell metacharacters.
An authenticated attacker with network reachability to the router web interface can submit a crafted request that appends shell operators to the targetAPSsid value. The router then executes the injected commands in the context of the web server process, which on embedded D-Link devices typically runs with elevated privileges. Successful exploitation yields command execution on the router itself, enabling configuration tampering, credential harvesting, or pivoting into the internal network.
Root Cause
The root cause is improper neutralization of special elements used in an OS command [CWE-77]. The formWsc handler concatenates the targetAPSsid argument into a shell command string without filtering characters such as ;, |, &, or backticks.
Attack Vector
Exploitation occurs over the network against the router administrative interface. The attacker must possess valid high-privilege credentials to reach the vulnerable endpoint. Once authenticated, a single HTTP POST request to /boafrm/formWsc containing a malicious targetAPSsid value triggers command execution. A public proof-of-concept demonstrating the request format is available on GitHub. See the GitHub PoC Gist and VulDB CVE-2026-90706 for technical details.
Detection Methods for CVE-2026-90706
Indicators of Compromise
- HTTP POST requests to /boafrm/formWsc containing shell metacharacters (;, |, &, `, $() in the targetAPSsid parameter.
- Unexpected outbound connections from the router to attacker-controlled infrastructure following administrative login events.
- Unauthorized modifications to router firmware, DNS settings, or firewall rules that follow requests to the formWsc endpoint.
Detection Strategies
- Inspect web server and management interface logs on the DWR-M921 for POST requests to /boafrm/formWsc where targetAPSsid contains non-SSID characters.
- Deploy network intrusion detection signatures that flag HTTP request bodies containing targetAPSsid= followed by shell operators.
- Correlate router administrative authentication events with subsequent anomalous outbound traffic from the device.
Monitoring Recommendations
- Forward router syslog output to a centralized log management platform for retention and search.
- Baseline normal WPS and Wi-Fi configuration changes and alert on activity outside of change windows.
- Monitor for new administrative accounts or altered credential hashes on affected routers.
How to Mitigate CVE-2026-90706
Immediate Actions Required
- Restrict access to the router administrative interface so it is not reachable from the WAN or untrusted network segments.
- Rotate administrative credentials on all DWR-M921 devices and enforce strong, unique passwords.
- Audit the router configuration and firmware integrity for evidence of tampering.
Patch Information
No vendor patch is referenced in the available advisory data at the time of publication. Consult the D-Link Official Website for the latest firmware releases and product support notices for the DWR-M921. Additional tracking is available through VulDB Vulnerability #403248.
Workarounds
- Disable remote administration of the router and limit management access to a dedicated internal VLAN.
- Place the DWR-M921 behind an upstream firewall that filters HTTP requests to /boafrm/formWsc from untrusted sources.
- Retire and replace end-of-support DWR-M921 devices where no vendor firmware update is available.
# Example: block external access to the router management interface
iptables -I INPUT -p tcp --dport 80 ! -s 192.0.2.0/24 -j DROP
iptables -I INPUT -p tcp --dport 443 ! -s 192.0.2.0/24 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
