CVE Alert: CVE-2025-12213 – Tenda – O3

Risk verdict

Critical risk: remote code execution is feasible on Tenda O3 via a stack-based overflow in setVlanConfig; a public exploit and PoC are available, enabling rapid weaponisation.

Why this matters

Compromising the router could give an attacker full control of the device, exfiltrate traffic, or pivot to other devices on the LAN. In typical consumer and small-office deployments, this creates rapid, broad attack surface across home networks and exposed perimeter devices.

Most likely attack path

No user interaction required from the attacker. From the internet, an adversary can target the WAN-facing /goform/setVlanConfig endpoint with a crafted lan parameter to trigger the overflow, enabling remote code execution. Once compromised, the router gateway can be used to monitor, modify, or block traffic and to pivot to connected hosts, with high impact given C/I/A are all elevated.

Who is most exposed

Primarily home users and small offices running Tenda O3 with WAN exposure or weakly protected remote management. Any deployment relying on consumer-grade routers as Internet edge is at risk, especially if remote administration is enabled.

Detection ideas

• Unusual HTTP POSTs to /goform/setVlanConfig with oversized or malformed lan values.
• Router crashes, reboots, or kernel/stack traces logged in system logs.
• Repeated attempts from external IPs to the router’s management interfaces.
• New VLAN or network topology changes without administrator action.
• Abrupt spikes in CPU/memory on the device.

Mitigation and prioritisation

• Apply the vendor fix to 1.0.0.10(2478) or newer immediately.
• Disable WAN/remote management unless explicitly required; bind management to trusted networks.
• Implement strict firewall rules to block unsolicited access to management endpoints; segment LAN from WAN where feasible.
• Monitor router logs for /goform/setVlanConfig activity and PoC indicators; deploy rapid IR if exploitation is detected.
• Schedule patch deployment during a maintenance window; verify compatibility in a test environment before wide rollout.