CVE-2025-11586: Tenda AC7 Buffer Overflow Vulnerability

CVE-2025-11586 Overview

CVE-2025-11586 is a stack-based buffer overflow vulnerability discovered in Tenda AC7 router firmware version 15.03.06.44. The vulnerability exists in the /goform/setNotUpgrade endpoint, where improper handling of the newVersion argument allows an attacker to trigger a buffer overflow condition. This firmware vulnerability affects an unknown function within the specified file and can be exploited remotely over the network. The exploit has been publicly disclosed, increasing the risk of active exploitation attempts against vulnerable devices.

Critical Impact

Remote attackers can exploit this stack-based buffer overflow to potentially achieve code execution on vulnerable Tenda AC7 routers, compromising device integrity and network security.

Affected Products

• Tenda AC7 Firmware version 15.03.06.44
• Tenda AC7 Hardware version 1.0
• tenda ac7_firmware

Discovery Timeline

• 2025-10-10 - CVE-2025-11586 published to NVD
• 2025-10-20 - Last updated in NVD database

Technical Details for CVE-2025-11586

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the firmware's web management interface, specifically in the function handling requests to /goform/setNotUpgrade. When processing the newVersion parameter, the application fails to properly validate the length of user-supplied input before copying it to a fixed-size stack buffer.

The attack can be initiated remotely with network access, requiring low privilege authentication. No user interaction is required for exploitation. Successful exploitation can result in high impact to confidentiality, integrity, and availability of the affected device, potentially allowing an attacker to execute arbitrary code with the privileges of the web server process running on the router.

Root Cause

The root cause of this vulnerability is improper bounds checking when handling the newVersion argument in the /goform/setNotUpgrade function. The firmware does not adequately validate the size of input data before performing memory copy operations to a stack-allocated buffer. This classic memory safety issue allows attackers to write beyond the intended buffer boundaries, potentially overwriting critical stack data including return addresses.

Attack Vector

The attack vector is network-based, allowing remote exploitation of vulnerable Tenda AC7 routers. An authenticated attacker with low privileges can send a specially crafted HTTP request to the /goform/setNotUpgrade endpoint containing an oversized newVersion parameter. The malicious payload overflows the stack buffer, enabling the attacker to corrupt adjacent memory regions and potentially hijack control flow.

The vulnerability is particularly dangerous in IoT environments where routers may be exposed to the internet or accessible from compromised internal networks. Exploitation could lead to complete device compromise, allowing attackers to intercept network traffic, pivot to other network resources, or use the device as part of a botnet.

For detailed technical analysis of this vulnerability, refer to the GitHub IoT Exploit Documentation.

Detection Methods for CVE-2025-11586

Indicators of Compromise

• Unusual HTTP POST requests to /goform/setNotUpgrade with abnormally large newVersion parameter values
• Unexpected router reboots or crashes indicating potential exploitation attempts
• Anomalous outbound network traffic from the router suggesting compromise
• Modified router configuration or firmware indicating successful exploitation

Detection Strategies

• Monitor network traffic for HTTP requests targeting /goform/setNotUpgrade with payloads exceeding normal parameter lengths
• Implement intrusion detection signatures to flag buffer overflow patterns in web management interface traffic
• Deploy network-level monitoring for connections to known malicious infrastructure from IoT devices
• Review router logs for authentication failures followed by administrative actions

Monitoring Recommendations

• Enable logging on the Tenda AC7 router if supported by the firmware
• Implement network segmentation to isolate IoT devices and monitor cross-segment traffic
• Deploy network anomaly detection to identify unusual traffic patterns from router management interfaces
• Regularly audit device configurations for unauthorized changes

How to Mitigate CVE-2025-11586

Immediate Actions Required

• Restrict network access to the router's web management interface to trusted IP addresses only
• Disable remote management features if not required for business operations
• Implement network segmentation to isolate vulnerable devices from critical network assets
• Monitor for exploitation attempts using the detection strategies outlined above

Patch Information

At the time of this writing, no official patch information has been released by Tenda for this vulnerability. Users should monitor the Tenda Official Website for firmware updates addressing CVE-2025-11586. Additional vulnerability details are tracked on VulDB #327908.

Workarounds

• Disable the web management interface entirely if not needed for device administration
• Implement strict firewall rules to block external access to the router's management ports
• Use a VPN or secure tunnel for remote administration instead of direct web interface access
• Consider replacing vulnerable devices with supported hardware if patches are not forthcoming

# Example firewall rule to restrict management interface access (iptables)
# Apply on upstream firewall or gateway device
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 only from trusted management network
iptables -I FORWARD -s <trusted_network>/24 -d <router_ip> -p tcp --dport 80 -j ACCEPT