CVE-2026-7081 Overview
CVE-2026-7081 is a buffer overflow vulnerability in the Tenda F456 router running firmware version 1.0.0.5. The flaw resides in the fromGstDhcpSetSer function of the /goform/GstDhcpSetSer endpoint handled by the httpd component. An attacker can trigger the overflow by manipulating the dips argument in a crafted HTTP request. Remote exploitation is possible over the network, and a public exploit is available. The vulnerability is classified under CWE-119, covering improper restriction of operations within the bounds of a memory buffer.
Critical Impact
Remote attackers with low-level privileges can corrupt memory on affected Tenda F456 devices, potentially achieving arbitrary code execution or denial of service against the router's web management service.
Affected Products
- Tenda F456 router (hardware)
- Tenda F456 Firmware version 1.0.0.5
- Devices exposing the httpd web management interface
Discovery Timeline
- 2026-04-27 - CVE-2026-7081 published to NVD
- 2026-04-30 - Last updated in NVD database
Technical Details for CVE-2026-7081
Vulnerability Analysis
The vulnerability exists in the fromGstDhcpSetSer function, which processes DHCP server configuration requests submitted to the /goform/GstDhcpSetSer endpoint. The function fails to validate the length of the dips parameter before copying it into a fixed-size stack or heap buffer. Supplying an oversized dips value overflows the destination buffer and corrupts adjacent memory regions.
Because the affected service is the embedded httpd daemon, successful exploitation can crash the management interface or, with a crafted payload, redirect execution flow. The exploit details have been published, increasing the likelihood of opportunistic scanning against exposed devices.
Root Cause
The root cause is missing bounds checking on attacker-controlled input within fromGstDhcpSetSer. The handler trusts the length of the dips argument and performs an unsafe copy operation, consistent with the [CWE-119] classification for improper buffer boundary enforcement. Embedded MIPS-based routers often lack modern memory protections such as ASLR and stack canaries, which amplifies the impact of memory corruption.
Attack Vector
Exploitation requires network access to the router's web administration interface and a low-privileged authenticated session. The attacker sends an HTTP POST request to /goform/GstDhcpSetSer with an oversized dips parameter. No user interaction is required. Devices that expose management interfaces to the WAN or to untrusted LAN segments are at the highest risk.
The vulnerability manifests when the httpd handler copies the malformed dips value into a fixed-size buffer without length validation. Refer to the VulDB #359656 advisory and the GitHub PoC Repository for technical details.
Detection Methods for CVE-2026-7081
Indicators of Compromise
- HTTP POST requests to /goform/GstDhcpSetSer containing abnormally long dips parameter values.
- Unexpected httpd process crashes or restarts on Tenda F456 devices.
- Router management interface becoming unresponsive following inbound HTTP traffic from untrusted sources.
Detection Strategies
- Inspect web access logs and network captures for requests targeting /goform/GstDhcpSetSer with payloads exceeding typical IP address string lengths.
- Deploy intrusion detection signatures matching oversized dips parameter values in HTTP request bodies destined for Tenda management endpoints.
- Baseline normal administrative traffic to the router and alert on anomalies in request size or frequency.
Monitoring Recommendations
- Forward router syslog and HTTP access logs to a centralized logging platform for retention and correlation.
- Monitor for repeated connection attempts to TCP ports hosting the router's web interface from external addresses.
- Track device uptime and service health metrics to identify crash-restart patterns indicative of exploitation attempts.
How to Mitigate CVE-2026-7081
Immediate Actions Required
- Restrict access to the router's web management interface to trusted management VLANs or specific administrator IP addresses.
- Disable remote WAN-side administration on all Tenda F456 devices.
- Rotate administrator credentials and enforce strong, unique passwords to limit access required for exploitation.
- Inventory all Tenda F456 devices running firmware 1.0.0.5 and prioritize them for remediation.
Patch Information
No vendor patch has been referenced in the published advisory at the time of disclosure. Monitor the Tenda Official Website for firmware updates addressing CVE-2026-7081. Until a fixed firmware version is released, apply the compensating controls listed below.
Workarounds
- Place affected routers behind a network firewall that blocks untrusted inbound access to the HTTP management port.
- Segment management traffic onto a dedicated VLAN that is isolated from general user and guest networks.
- Replace end-of-life Tenda F456 units with supported hardware if no vendor firmware update becomes available.
# Example: restrict access to router management interface using iptables on an upstream gateway
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -s <admin_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.
