CVE-2025-11388: Tenda AC15 Buffer Overflow Vulnerability

CVE-2025-11388 Overview

CVE-2025-11388 is a stack-based buffer overflow vulnerability in the Tenda AC15 router running firmware version 15.03.05.18. The flaw resides in the /goform/setNotUpgrade endpoint, where the newVersion argument is processed without proper bounds checking. An attacker with low-level network access can manipulate this argument to overflow the fixed-size stack buffer. The vulnerability is remotely exploitable and public technical documentation describing the issue is available. The weakness is tracked under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer).

Critical Impact
Remote attackers can overflow the stack via the newVersion parameter to corrupt memory, crash the device, or potentially achieve arbitrary code execution on the router.

Affected Products

Tenda AC15 router (hardware)
Tenda AC15 firmware version 15.03.05.18
Devices exposing the /goform/setNotUpgrade web management endpoint

Discovery Timeline

2025-10-07 - CVE-2025-11388 published to NVD
2025-10-09 - Last updated in NVD database

Technical Details for CVE-2025-11388

Vulnerability Analysis

The Tenda AC15 web management interface exposes the /goform/setNotUpgrade handler, which accepts a newVersion parameter from authenticated users. The handler copies the user-supplied value into a fixed-size stack buffer without validating the input length. Supplying an oversized string overwrites adjacent stack memory, including saved return addresses and frame pointers.

Because Tenda AC15 firmware runs on a MIPS-based embedded Linux platform with limited memory protections, stack corruption can lead to control-flow hijacking. Successful exploitation grants attackers execution within the router's httpd process context, which typically runs with elevated privileges on consumer routers.

Root Cause

The root cause is the absence of length validation on the newVersion HTTP parameter before it is copied into a local stack buffer, consistent with CWE-119. The handler relies on unsafe string-copy routines that do not enforce destination buffer boundaries. This pattern is common across Tenda's /goform/ request handlers and has produced multiple historical CVEs in the AC15 product line.

Attack Vector

Exploitation requires network reachability to the router's management interface and low-privilege authenticated access. An attacker crafts an HTTP POST request to /goform/setNotUpgrade containing an overlong newVersion value. The malformed request triggers the overflow on the device's HTTP service. Public proof-of-concept documentation is hosted in the GitHub IoT vulnerability repository, which details the vulnerable code path and request format. No verified exploit code is reproduced here.

Detection Methods for CVE-2025-11388

Indicators of Compromise

HTTP POST requests to /goform/setNotUpgrade containing abnormally long newVersion parameter values
Unexpected reboots or httpd process crashes on Tenda AC15 devices
Outbound connections from the router to unfamiliar IP addresses following management-interface activity
New or modified administrative accounts on the device

Detection Strategies

Inspect web server and reverse-proxy logs for requests to /goform/setNotUpgrade with parameter lengths exceeding typical version-string sizes
Deploy network intrusion detection signatures that flag POST bodies to Tenda /goform/ endpoints containing oversized fields
Monitor router syslog output for segmentation faults, watchdog resets, or repeated httpd restarts

Monitoring Recommendations

Restrict and log all access to router administrative interfaces from the LAN and WAN sides
Capture network traffic destined for management ports and baseline normal administrative request sizes
Alert on management-interface authentication events originating from non-administrative subnets

How to Mitigate CVE-2025-11388

Immediate Actions Required

Disable remote (WAN-side) administration on Tenda AC15 devices immediately
Restrict LAN access to the router web interface to a dedicated management VLAN or trusted host
Rotate administrative credentials and disable any unused accounts on the device
Inventory all Tenda AC15 units running firmware 15.03.05.18 and prioritize replacement or isolation

Patch Information

As of the last NVD modification on 2025-10-09, no vendor advisory or fixed firmware release has been published on the Tenda official website. Additional vulnerability metadata is tracked at VulDB entry 327315. Administrators should monitor Tenda's support channels for an updated firmware image addressing the setNotUpgrade handler.

Workarounds

Place the router behind a network segment that blocks untrusted clients from reaching TCP/80 and TCP/443 on the device
Use an upstream firewall to drop HTTP requests to /goform/setNotUpgrade until a vendor patch is available
Where feasible, replace end-of-support consumer routers with current-generation hardware that receives active firmware maintenance

bash

# Example upstream firewall rule to block access to the vulnerable endpoint
# (adjust ROUTER_IP and interfaces to your environment)
iptables -I FORWARD -d <ROUTER_IP> -p tcp --dport 80 \
  -m string --algo bm --string "/goform/setNotUpgrade" -j DROP