CVE-2026-11499 Overview
CVE-2026-11499 is a stack-based buffer overflow vulnerability affecting Tenda HG7, HG9, and HG10 routers running firmware version 300001138_en_xpon. The flaw resides in the formDOMAINBLK function within the /boaform/formDOMAINBLK endpoint. An attacker can manipulate the blkDomain argument to overflow the stack buffer and corrupt adjacent memory. The vulnerability is exploitable remotely over the network without authentication or user interaction. The weakness is classified under CWE-119, improper restriction of operations within the bounds of a memory buffer. A public proof-of-concept is referenced in the GitHub PoC Repository.
Critical Impact
Remote unauthenticated attackers can trigger stack corruption in the formDOMAINBLK handler, potentially leading to arbitrary code execution or device compromise on affected Tenda HG7, HG9, and HG10 routers.
Affected Products
- Tenda HG7 router running firmware 300001138_en_xpon
- Tenda HG9 router running firmware 300001138_en_xpon
- Tenda HG10 router running firmware 300001138_en_xpon
Discovery Timeline
- 2026-06-08 - CVE-2026-11499 published to the National Vulnerability Database
- 2026-06-08 - Last updated in NVD database
Technical Details for CVE-2026-11499
Vulnerability Analysis
The vulnerability exists in the formDOMAINBLK function exposed through the /boaform/formDOMAINBLK web interface endpoint on affected Tenda routers. The function processes the blkDomain HTTP request parameter and copies its contents into a fixed-size stack buffer without enforcing length validation. When an attacker submits an oversized blkDomain value, the copy operation writes beyond the buffer bounds and overwrites adjacent stack memory, including saved frame pointers and return addresses.
The boa HTTP server commonly used in Tenda firmware runs with elevated privileges on the device, meaning successful exploitation grants attacker-controlled execution in the same security context. Attackers can leverage the corruption to redirect execution flow, achieve remote code execution, or cause persistent denial of service on the device.
Root Cause
The root cause is missing bounds checking on the blkDomain parameter before it is copied into a stack-allocated buffer inside formDOMAINBLK. The handler relies on unsafe string-copy semantics and trusts attacker-supplied input length. This mismatch between the input size and the destination buffer capacity produces the classic stack-based buffer overflow condition described by CWE-119.
Attack Vector
The attack is performed remotely over the network against the router's HTTP management interface. An attacker sends a crafted HTTP request to /boaform/formDOMAINBLK containing an oversized blkDomain parameter value. No authentication or user interaction is required when the management interface is reachable. Devices exposing the web interface to the WAN or to untrusted network segments are at the highest risk. Details of the attack pattern are documented in the VulDB CVE Details entry and the GitHub PoC Repository.
Detection Methods for CVE-2026-11499
Indicators of Compromise
- HTTP POST requests targeting /boaform/formDOMAINBLK with abnormally long blkDomain parameter values
- Unexpected reboots, crashes, or watchdog resets on Tenda HG7, HG9, or HG10 routers
- New or unknown outbound connections originating from the router management plane
- Configuration changes to domain blocking rules that were not initiated by an administrator
Detection Strategies
- Inspect web server and reverse-proxy logs for requests to /boaform/formDOMAINBLK with blkDomain payloads exceeding expected domain-name length limits
- Deploy network IDS signatures that match oversized HTTP form parameters destined for the boa web server on Tenda devices
- Correlate router crash events with preceding inbound HTTP requests to the /boaform/ URI namespace
Monitoring Recommendations
- Continuously monitor management-plane HTTP traffic to consumer-grade routers for anomalous parameter sizes
- Alert on any external (WAN-side) access attempts to router administration endpoints
- Track firmware version inventory to identify devices still running 300001138_en_xpon
How to Mitigate CVE-2026-11499
Immediate Actions Required
- Restrict access to the router web administration interface so it is reachable only from trusted LAN management hosts
- Disable WAN-side remote management on all affected Tenda HG7, HG9, and HG10 devices
- Place vulnerable devices behind a network segment with strict ingress filtering until a vendor patch is available
- Monitor the Tenda Official Website for firmware updates addressing CVE-2026-11499
Patch Information
At the time of publication, no vendor patch for CVE-2026-11499 has been documented in the referenced advisories. Administrators should track the VulDB Vulnerability Info entry and the Tenda Official Website for firmware releases superseding 300001138_en_xpon.
Workarounds
- Block inbound HTTP and HTTPS access to the router management interface from untrusted networks using upstream firewall rules
- Apply ACLs that limit access to /boaform/ URIs to specific administrator IP addresses
- Replace end-of-life or unpatched consumer-grade routers with current models that receive active vendor security maintenance
# Example upstream firewall rule to block external access to router admin interface
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -i <wan_iface> -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -i <wan_iface> -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
