CVE-2026-36789: Shenzhen Tenda Technology Co

Synopsis

Multiple stack-based buffer overflows exist in the Tenda AC1206 router firmware (v15.03.06.23), specifically in the fromGstDhcpSetSer function, triggered through the username and password HTTP request parameters. The vulnerabilities are reachable over the network without any authentication or user interaction. Successful exploitation causes the device to crash, resulting in a denial of service. HarborGuard is tracking the advisory and will make a patched rebuild available as soon as an upstream fix is published.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The vulnerable HTTP endpoint is exposed over the network, so an attacker must be able to reach the device's web interface to send the crafted request.

• AuthenticationNot required

  No credentials are needed; the overflow is triggered through parameters processed before any authentication check.

• Victim interactionNot required

  The attack is fully remote and automated; no user on the target device needs to take any action.

• Attack complexityDetail

  Exploitation is straightforward and condition-free; an attacker only needs to send a crafted HTTP request with an oversized username or password parameter.

Blast Radius

• Crashes the affected Tenda AC1206 router process, taking the device offline and cutting network connectivity for all clients behind it.
• Repeated exploitation keeps the device in a crashed or reboot loop, sustaining the outage without further attacker effort.
• No confidentiality or integrity impact is indicated; the attacker gains no access to data and cannot modify stored configuration.