CVE-2025-1814: Tenda AC6 Buffer Overflow Vulnerability

CVE-2025-1814 Overview

CVE-2025-1814 is a stack-based buffer overflow vulnerability in the Tenda AC6 router running firmware version 15.03.05.16. The flaw resides in the /goform/WifiExtraSet endpoint, where the wpapsk_crypto argument is processed without proper bounds checking. Attackers can trigger the overflow remotely over the network with low privileges, corrupting stack memory on the affected device. The exploit details have been publicly disclosed, increasing the risk of opportunistic abuse against exposed devices. The vulnerability impacts the confidentiality, integrity, and availability of the router, with potential for arbitrary code execution on the embedded Linux platform.

Critical Impact

Remote attackers can exploit the wpapsk_crypto parameter on /goform/WifiExtraSet to corrupt stack memory on Tenda AC6 routers, potentially leading to arbitrary code execution and full device compromise.

Affected Products

• Tenda AC6 router (hardware)
• Tenda AC6 firmware version 15.03.05.16
• Deployments exposing the web management interface to untrusted networks

Discovery Timeline

• 2025-03-02 - CVE-2025-1814 published to NVD
• 2025-03-05 - Last updated in NVD database

Technical Details for CVE-2025-1814

Vulnerability Analysis

The vulnerability is a stack-based buffer overflow [CWE-121] in the HTTP request handler for the /goform/WifiExtraSet endpoint. The handler reads the wpapsk_crypto parameter from the incoming request and copies it into a fixed-size stack buffer without validating the input length. Supplying an oversized value overwrites adjacent stack memory, including saved registers and the return address.

The underlying weaknesses are tracked as [CWE-119] (improper restriction of operations within memory buffer bounds) and [CWE-787] (out-of-bounds write). Because the affected MIPS-based firmware lacks robust modern exploit mitigations, a crafted payload can hijack control flow and execute attacker-supplied instructions in the context of the web management daemon, typically running as root.

Root Cause

The root cause is missing length validation when handling user-controlled HTTP parameters in the goform handler. The application uses unbounded string operations to move request data into a stack buffer, violating safe memory handling practices for embedded web servers.

Attack Vector

An authenticated attacker with low-privilege access to the router web interface sends a crafted POST request to /goform/WifiExtraSet with an oversized wpapsk_crypto value. The malformed value overflows the destination buffer, corrupting saved control data on the stack. No user interaction is required. The attack surface expands significantly when the device exposes its management interface to the WAN or to untrusted Wi-Fi networks.

The vulnerability mechanism is described in the public proof-of-concept writeup. See the GitHub PoC Repository and VulDB entry #298082 for technical details.

Detection Methods for CVE-2025-1814

Indicators of Compromise

• HTTP POST requests to /goform/WifiExtraSet containing abnormally long wpapsk_crypto parameter values
• Unexpected reboots, crashes, or web daemon restarts on Tenda AC6 devices
• Outbound connections from the router to unfamiliar IP addresses following suspicious HTTP traffic
• Configuration changes to Wi-Fi or routing settings that do not match administrator activity

Detection Strategies

• Inspect web access logs and network captures for POST requests to /goform/WifiExtraSet with parameter values exceeding expected byte lengths
• Deploy network intrusion detection signatures that flag oversized wpapsk_crypto values destined for Tenda AC6 management interfaces
• Correlate router crash events with preceding inbound HTTP traffic to identify exploitation attempts

Monitoring Recommendations

• Centralize syslog output from Tenda AC6 devices and alert on web daemon segmentation faults or unexpected restarts
• Monitor LAN and WAN traffic for repeated requests to /goform/ endpoints from non-administrative sources
• Track firmware version and configuration drift across managed routers to detect unauthorized modifications

How to Mitigate CVE-2025-1814

Immediate Actions Required

• Restrict access to the router web management interface to trusted management VLANs only
• Disable remote (WAN-side) administration on all Tenda AC6 devices running firmware 15.03.05.16
• Rotate administrative credentials and enforce strong, unique passwords to limit low-privilege access required for exploitation
• Segment vulnerable routers from sensitive internal systems until a fix is available

Patch Information

At the time of publication, no vendor patch is referenced in the NVD entry or VulDB submission. Administrators should consult the Tenda Official Website for firmware updates and security advisories. Replace end-of-life Tenda AC6 hardware where vendor support is no longer provided.

Workarounds

• Place affected routers behind an upstream firewall that filters inbound HTTP and HTTPS to the management interface
• Apply ACLs that limit /goform/WifiExtraSet access to specific administrative source IP addresses
• Disable Wi-Fi remote configuration features that route through the vulnerable endpoint when not in use
• Consider replacing the device with a supported model if firmware remediation is not available

# Configuration example: block external access to the router web UI on an upstream Linux firewall
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -m state --state NEW -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -m state --state NEW -j DROP
# Allow only the management subnet
iptables -I FORWARD -p tcp -s 10.10.0.0/24 -d <router_ip> --dport 80 -j ACCEPT