CVE-2025-12595: Tenda AC23 Buffer Overflow Vulnerability

CVE-2025-12595 Overview

CVE-2025-12595 is a buffer overflow vulnerability in Tenda AC23 routers running firmware version 16.03.07.52. The flaw resides in the formSetVirtualSer function handling requests to /goform/SetVirtualServerCfg. Attackers manipulate the list argument to trigger memory corruption [CWE-119, CWE-120]. The exploit has been publicly disclosed, and the issue is remotely exploitable across the network. Successful exploitation can compromise confidentiality, integrity, and availability of the affected device.

Critical Impact
Remote attackers with low privileges can trigger a buffer overflow on Tenda AC23 routers, potentially leading to arbitrary code execution or denial of service against the network gateway.

Affected Products

Tenda AC23 router (hardware revision 1.0)
Tenda AC23 firmware version 16.03.07.52
Deployments exposing the /goform/SetVirtualServerCfg endpoint

Discovery Timeline

2025-11-02 - CVE-2025-12595 published to NVD
2026-02-24 - Last updated in NVD database

Technical Details for CVE-2025-12595

Vulnerability Analysis

The vulnerability exists in the formSetVirtualSer function within the Tenda AC23 web management interface. This function processes virtual server configuration submitted through the /goform/SetVirtualServerCfg endpoint. The handler reads the list parameter from the HTTP request and copies its contents into a fixed-size stack buffer without validating the input length. When the supplied data exceeds the destination buffer, adjacent stack memory is overwritten, including saved return addresses.

This classic stack-based buffer overflow allows attackers to corrupt control-flow data. On MIPS-based Tenda devices, attackers commonly chain return-oriented programming (ROP) gadgets to bypass non-executable stack protections and achieve arbitrary code execution. Public exploit details have been published, lowering the barrier for opportunistic attacks against exposed devices.

Root Cause

The root cause is improper restriction of operations within the bounds of a memory buffer [CWE-119] combined with a classic buffer copy without checking the size of input [CWE-120]. The formSetVirtualSer function trusts attacker-controlled length for the list argument and performs an unbounded copy into a fixed stack buffer.

Attack Vector

The attack vector is the network. An attacker authenticated with low privileges sends a crafted HTTP POST request to /goform/SetVirtualServerCfg with an oversized list parameter. No user interaction is required. If the device's web interface is exposed to the WAN, exploitation is reachable directly from the internet. See the GitHub Issue Report and VulDB entry #330890 for additional technical details.

Detection Methods for CVE-2025-12595

Indicators of Compromise

HTTP POST requests to /goform/SetVirtualServerCfg containing oversized list parameter values
Unexpected reboots, crashes, or service interruptions on the router's httpd web management process
Outbound connections from the router to unfamiliar command-and-control hosts following inbound configuration requests
New or unexpected virtual server (port forwarding) rules on the device configuration

Detection Strategies

Inspect HTTP request bodies destined for the Tenda admin interface and alert on list parameter values exceeding typical lengths
Deploy network signatures targeting requests to /goform/SetVirtualServerCfg with anomalous payload sizes
Correlate failed authentication attempts followed by successful POSTs to virtual server configuration endpoints

Monitoring Recommendations

Restrict access logging on the router web UI and forward logs to a centralized SIEM for analysis
Monitor for changes to port forwarding rules and DNS configurations on edge routers
Track router availability and crash patterns that may indicate exploitation attempts

How to Mitigate CVE-2025-12595

Immediate Actions Required

Disable remote (WAN-side) management of the Tenda AC23 web interface immediately
Restrict LAN access to the /goform/SetVirtualServerCfg endpoint to trusted administrative hosts only
Rotate the router administrator credentials and enforce strong, unique passwords
Audit existing virtual server rules and remove any unauthorized port forwarding entries

Patch Information

As of the latest NVD update, no vendor patch has been published for Tenda AC23 firmware 16.03.07.52. Monitor the Tenda website for firmware updates addressing this issue. Consider replacing affected devices if a fix is not released in a reasonable timeframe.

Workarounds

Place the router behind an upstream firewall and block external access to TCP ports used by the web management interface
Segment the network so that untrusted clients cannot reach the router administration interface
Disable any unused services (UPnP, remote management, cloud features) that expose configuration endpoints

bash

# Example upstream firewall rule blocking external access to router admin
iptables -A FORWARD -d <router_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router_ip> -p tcp --dport 443 -j DROP