CVE-2025-1814: Tenda AC6 Buffer Overflow Vulnerability

CVE-2025-1814 Overview

A critical stack-based buffer overflow vulnerability has been identified in Tenda AC6 router firmware version 15.03.05.16. The vulnerability exists in the /goform/WifiExtraSet endpoint, where improper handling of the wpapsk_crypto argument allows attackers to trigger a buffer overflow condition. This vulnerability can be exploited remotely over the network by authenticated attackers to potentially achieve arbitrary code execution on the affected device.

Critical Impact

Remote attackers can exploit this stack-based buffer overflow to compromise the integrity, confidentiality, and availability of affected Tenda AC6 routers. Successful exploitation could lead to complete device takeover, allowing attackers to intercept network traffic, modify router configurations, or use the device as a pivot point for further attacks within the network.

Affected Products

• Tenda AC6 Firmware version 15.03.05.16
• Tenda AC6 Hardware

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

This vulnerability is classified under CWE-787 (Out-of-bounds Write) and CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the web management interface of the Tenda AC6 router, specifically within the /goform/WifiExtraSet form handler functionality.

The vulnerability occurs when the router processes the wpapsk_crypto parameter without proper bounds checking. When an attacker supplies a specially crafted input exceeding the expected buffer size, the data overflows the allocated stack buffer, potentially overwriting adjacent memory including return addresses and other critical control flow data.

The network-accessible nature of this vulnerability significantly increases its risk profile, as attackers do not require physical access to the device to initiate an attack. Low attack complexity combined with the potential for complete system compromise makes this a priority vulnerability for remediation.

Root Cause

The root cause of this vulnerability is insufficient input validation in the WifiExtraSet form handler. The affected code fails to properly validate the length of the wpapsk_crypto parameter before copying it into a fixed-size stack buffer. This classic buffer overflow pattern allows attackers to write beyond the allocated memory region, corrupting stack memory and potentially hijacking program execution flow.

Attack Vector

The attack vector is network-based, targeting the router's web management interface. An authenticated attacker can send a malicious HTTP POST request to the /goform/WifiExtraSet endpoint with an oversized wpapsk_crypto parameter value. The vulnerability requires low privileges to exploit and does not require user interaction, making automated exploitation feasible.

The exploitation typically follows this pattern: an attacker crafts a payload containing shellcode or return-oriented programming (ROP) chains, then sends this payload via the vulnerable form parameter. When the buffer overflow occurs, the attacker's payload overwrites the return address on the stack, redirecting execution to attacker-controlled code.

Technical details and proof-of-concept information have been publicly disclosed. For detailed exploitation information, refer to the GitHub PoC Repository.

Detection Methods for CVE-2025-1814

Indicators of Compromise

• Unusual HTTP POST requests to /goform/WifiExtraSet with abnormally large wpapsk_crypto parameter values
• Router crashes or unexpected reboots indicating potential exploitation attempts
• Unauthorized configuration changes on affected Tenda AC6 devices
• Suspicious outbound network connections from the router to unknown external hosts

Detection Strategies

• Implement network intrusion detection rules to monitor for oversized POST requests targeting /goform/WifiExtraSet
• Deploy web application firewall rules to filter requests with excessively long parameter values to the router's management interface
• Monitor router logs for failed authentication attempts followed by unusual form submissions
• Use SentinelOne Singularity to detect anomalous behavior patterns indicative of IoT device compromise

Monitoring Recommendations

• Enable verbose logging on network security appliances monitoring traffic to/from Tenda AC6 devices
• Establish baseline network behavior for IoT devices and alert on deviations
• Implement continuous vulnerability scanning to identify unpatched Tenda AC6 routers in your environment

How to Mitigate CVE-2025-1814

Immediate Actions Required

• Restrict access to the router's web management interface to trusted networks only
• Disable remote management capabilities if not explicitly required
• Place affected Tenda AC6 routers behind a firewall with strict ingress filtering
• Implement network segmentation to isolate IoT devices from critical network assets
• Monitor for vendor security patches and apply immediately upon release

Patch Information

As of the last update on 2025-03-05, no official patch has been released by Tenda for this vulnerability. Users should monitor the Tenda Official Site for security updates and firmware releases. Additional vulnerability tracking information is available through VulDB #298082.

Workarounds

• Configure firewall rules to block external access to the router's management interface on port 80/443
• Use access control lists (ACLs) to restrict management interface access to specific trusted IP addresses
• Consider replacing affected devices with alternative hardware if no patch is forthcoming
• Implement VPN-only access for router management to reduce attack surface

# Example iptables rule to restrict management access (apply on upstream firewall)
# Block external access to Tenda router management interface
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 443 -j DROP

# Allow management only from trusted admin network
iptables -I FORWARD -s <ADMIN_NETWORK>/24 -d <ROUTER_IP> -p tcp --dport 80 -j ACCEPT