CVE-2025-45779: Tenda AC10 Buffer Overflow Vulnerability

CVE-2025-45779 Overview

CVE-2025-45779 is a critical buffer overflow vulnerability affecting Tenda AC10 routers running firmware version V1.0re_V15.03.06.46. The vulnerability exists in the formSetPPTPUserList handler and can be triggered through a maliciously crafted list POST parameter. This firmware vulnerability allows remote attackers to potentially execute arbitrary code or cause a denial of service condition on affected network devices without requiring authentication.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability over the network without authentication, potentially gaining complete control of the affected Tenda AC10 router or causing device crashes that disrupt network connectivity.

Affected Products

• Tenda AC10 Firmware version 15.03.06.46
• Tenda AC10 Hardware version 1.0
• Tenda AC10 V1.0re_V15.03.06.46

Discovery Timeline

• May 12, 2025 - CVE-2025-45779 published to NVD
• June 13, 2025 - Last updated in NVD database

Technical Details for CVE-2025-45779

Vulnerability Analysis

This buffer overflow vulnerability (CWE-120: Buffer Copy without Checking Size of Input) resides in the web management interface of the Tenda AC10 router. The formSetPPTPUserList function, which handles PPTP VPN user configuration, fails to properly validate the length of user-supplied input in the list POST parameter before copying it to a fixed-size buffer in memory.

When an attacker sends an HTTP POST request with an oversized list parameter to the vulnerable endpoint, the data overflows the allocated buffer boundaries. This can overwrite adjacent memory regions including return addresses on the stack, function pointers, or other critical data structures. The vulnerability can be exploited remotely over the network, requires no user interaction, and does not require authentication, making it particularly dangerous for exposed devices.

Root Cause

The root cause of CVE-2025-45779 is the use of unsafe memory copy operations in the formSetPPTPUserList handler without implementing proper bounds checking on the incoming list parameter. The firmware code allocates a fixed-size buffer but does not validate that the user-supplied input fits within this buffer before performing the copy operation, violating secure coding practices for embedded systems.

Attack Vector

The attack vector is network-based, targeting the HTTP-based web management interface typically accessible on the local network or potentially exposed to the internet if the device is misconfigured. An attacker can craft a malicious HTTP POST request to the formSetPPTPUserList endpoint containing an oversized list parameter.

The vulnerability can be exploited by sending a specially crafted POST request to the affected endpoint. Technical details and proof-of-concept information are available in the GitHub CVE-2025-45779 PoC repository. The overflow occurs when the firmware processes the oversized input, potentially allowing code execution with router privileges or causing the device to crash and reboot.

Detection Methods for CVE-2025-45779

Indicators of Compromise

• Unexpected router reboots or crashes, particularly when the web interface is accessed
• Anomalous HTTP POST requests targeting /goform/SetPPTPUserList or similar PPTP configuration endpoints
• Unusually large HTTP request bodies in POST requests to the router management interface
• Modified router configurations or unauthorized PPTP user entries
• Network traffic anomalies indicating potential command and control communications from the router

Detection Strategies

• Implement network-based intrusion detection rules to monitor for oversized POST requests to Tenda router management endpoints
• Deploy web application firewall (WAF) rules to filter malformed or oversized parameters in requests to IoT device interfaces
• Monitor for unusual outbound connections from router IP addresses that may indicate successful exploitation
• Use vulnerability scanning tools to identify Tenda AC10 devices running vulnerable firmware version 15.03.06.46

Monitoring Recommendations

• Enable logging on network firewalls to capture traffic to and from router management interfaces
• Set up alerts for HTTP POST requests exceeding normal size thresholds directed at IoT devices
• Monitor router uptime metrics and investigate unexpected restarts
• Implement network segmentation to isolate IoT devices and simplify traffic monitoring

How to Mitigate CVE-2025-45779

Immediate Actions Required

• Restrict access to the Tenda AC10 web management interface to trusted IP addresses only
• Disable remote management access from WAN interfaces immediately
• Implement network segmentation to isolate the affected router from critical network assets
• Check for firmware updates from Tenda and apply any available security patches
• Consider replacing affected devices if no patch becomes available

Patch Information

At the time of publication, no official patch has been confirmed for this vulnerability. Administrators should monitor the Tenda Firmware Download page for updated firmware releases that address CVE-2025-45779. Until a patch is available, implement the workarounds listed below to reduce exposure.

Workarounds

• Disable the web-based management interface if not required for operations
• Use firewall rules to block external access to the router's management ports (typically TCP 80 and 443)
• Implement MAC address filtering and strong wireless security to limit local network access
• Deploy a VPN or jump host to access router management instead of direct exposure
• Consider using an alternative router from a vendor with faster security response times

# Example iptables rules to restrict management interface access
# Allow management access only from trusted admin subnet
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP