CVE-2026-36792 Overview
CVE-2026-36792 is a stack-based buffer overflow vulnerability [CWE-121] in the Shenzhen Tenda Technology Co., Ltd Tenda W3 Wireless Router, firmware version v1.0.0.3(2204). The flaw resides in the formWifiRadioSet function, where the wl_radio parameter is processed without proper bounds checking. A remote attacker can send a crafted HTTP request to overflow the stack buffer, causing the router's web service to crash and resulting in a Denial of Service (DoS) condition.
Critical Impact
Unauthenticated remote attackers can trigger a Denial of Service on affected Tenda W3 routers via a single crafted HTTP request, disrupting network connectivity for all downstream clients.
Affected Products
- Shenzhen Tenda Technology Co., Ltd Tenda W3 Wireless Router
- Firmware version v1.0.0.3(2204)
- formWifiRadioSet HTTP handler component
Discovery Timeline
- 2026-06-09 - CVE-2026-36792 published to NVD
- 2026-06-10 - Last updated in NVD database
Technical Details for CVE-2026-36792
Vulnerability Analysis
The vulnerability exists in the formWifiRadioSet function within the web management interface of the Tenda W3 router. This handler processes HTTP POST requests used to configure the wireless radio settings. The wl_radio parameter, supplied by the client in the request body, is copied into a fixed-size stack buffer without enforcing the destination buffer's length.
When the supplied value exceeds the allocated stack space, adjacent stack memory — including saved registers and the return address — is overwritten. The corrupted control data causes the httpd process to crash, terminating the management interface and associated network services. Because the router architecture commonly co-locates routing and management functions, the crash interrupts traffic forwarding for connected clients.
Root Cause
The root cause is the use of unbounded string copy operations on user-controlled input. The formWifiRadioSet function does not validate the length of the wl_radio parameter before copying it into a local stack buffer, classifying the defect as a classic stack-based buffer overflow [CWE-121].
Attack Vector
Exploitation requires network access to the router's HTTP management interface. The attack does not require authentication, user interaction, or elevated privileges. An attacker sends a single crafted HTTP request with an oversized wl_radio parameter value to the formWifiRadioSet endpoint. The malformed request triggers the overflow and crashes the service. Proof-of-concept details are available in the GitHub PoC Repository.
The vulnerability impacts availability only; confidentiality and integrity are not directly affected based on current analysis. EPSS data places exploitation probability at 0.254%.
Detection Methods for CVE-2026-36792
Indicators of Compromise
- Unexpected reboots or crashes of the Tenda W3 router httpd process or management interface.
- Inbound HTTP POST requests targeting the formWifiRadioSet endpoint with abnormally long wl_radio parameter values.
- Loss of network connectivity for clients connected to the affected router following inbound WAN-side HTTP traffic.
Detection Strategies
- Inspect HTTP request bodies at network choke points for wl_radio parameter values exceeding expected length (typically a short alphanumeric token).
- Deploy network intrusion detection signatures matching POST requests to /goform/formWifiRadioSet containing oversized parameter payloads.
- Correlate router availability monitoring data with web-facing HTTP request logs to identify crash-inducing traffic patterns.
Monitoring Recommendations
- Enable syslog forwarding from the router to a centralized log collector to capture service crash events.
- Monitor management-interface uptime and alert on unexpected restarts of httpd.
- Track inbound HTTP traffic to administrative endpoints from untrusted networks.
How to Mitigate CVE-2026-36792
Immediate Actions Required
- Restrict access to the router's HTTP management interface to trusted LAN segments only; disable WAN-side administration.
- Place affected Tenda W3 devices behind a network firewall that blocks untrusted inbound HTTP traffic.
- Inventory all Tenda W3 devices running firmware v1.0.0.3(2204) and prioritize them for remediation.
Patch Information
At the time of publication, no vendor advisory or fixed firmware version has been published for CVE-2026-36792. Administrators should monitor the Tenda official support portal for firmware updates addressing the formWifiRadioSet stack overflow.
Workarounds
- Disable remote (WAN) management on the router's administrative settings page.
- Apply ACLs on upstream network equipment to restrict HTTP and HTTPS access to the router's management IP.
- Replace affected devices with supported hardware if patches are not released within an acceptable risk window.
- Segment IoT and consumer-grade networking equipment onto isolated VLANs to limit blast radius from a DoS condition.
# Example: block inbound HTTP to router management interface using iptables
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -s <trusted_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
