CVE-2026-51843: Tenda AC7 v15

Synopsis

Stack-based buffer overflow in the Tenda AC7 v15.03.06.44 firmware allows a remote, unauthenticated attacker to send a crafted request to the /goform/AdvSetMacMtuWan interface via the wanMTU parameter. The vulnerability is reachable over the network with no credentials required and no user interaction needed. Successful exploitation gives the attacker full read, write, and execution capability on the device, enabling remote code execution. No upstream fix has been published; HarborGuard tracks the advisory for patch availability.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The vulnerable interface is exposed over the network, so an attacker must be able to reach the device's web management service remotely.

• AuthenticationNot required

  No credentials of any privilege level are needed to send a malicious wanMTU parameter to the affected endpoint.

• Victim interactionNot required

  The attacker sends a crafted HTTP request directly to the device; no user action or click is required.

• Attack complexityDetail

  Exploit conditions are straightforward and reliable, with no race conditions, memory-layout dependencies, or special environmental factors required.

Blast Radius

• Attacker achieves remote code execution on the device, gaining full control of the firmware runtime.
• All data handled by the device, including network credentials, configuration secrets, and traffic passing through it, is readable by the attacker.
• The attacker can modify device configuration, redirect traffic, or inject malicious routing rules.
• The device can be crashed or rendered inoperable, disrupting network connectivity for all hosts behind it.