CVE-2025-1853: Tenda AC8 Buffer Overflow Vulnerability

CVE-2025-1853 Overview

A critical stack-based buffer overflow vulnerability has been discovered in Tenda AC8 routers running firmware version 16.03.34.06. This vulnerability affects the sub_49E098 function located in the /goform/SetIpMacBind component of the Parameter Handler. Improper handling of the list argument allows remote attackers to trigger a stack-based buffer overflow, potentially leading to remote code execution or denial of service on affected devices.

Critical Impact

Remote attackers with low-level privileges can exploit this stack-based buffer overflow to compromise Tenda AC8 routers, potentially gaining full control of the device or causing denial of service.

Affected Products

• Tenda AC8 Firmware version 16.03.34.06
• Tenda AC8 hardware devices

Discovery Timeline

• 2025-03-03 - CVE-2025-1853 published to NVD
• 2025-03-05 - Last updated in NVD database

Technical Details for CVE-2025-1853

Vulnerability Analysis

This vulnerability exists due to insufficient bounds checking in the sub_49E098 function when processing user-supplied input through the list parameter. When a maliciously crafted request is sent to the /goform/SetIpMacBind endpoint, the function fails to properly validate the size of the incoming data before copying it to a stack-allocated buffer.

The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-787 (Out-of-bounds Write), indicating that the fundamental issue lies in memory boundary violations during write operations.

Root Cause

The root cause of this vulnerability is improper input validation in the Parameter Handler component. The sub_49E098 function does not adequately check the length of the list argument before processing it, allowing attackers to supply oversized input that overwrites adjacent memory on the stack. This classic buffer overflow pattern is particularly dangerous on embedded devices like routers, which often lack modern memory protection mechanisms such as ASLR or stack canaries.

Attack Vector

The attack can be initiated remotely over the network by authenticated users with low-level privileges. An attacker must craft a specially formatted HTTP POST request to the /goform/SetIpMacBind endpoint containing a malicious list parameter. When processed by the vulnerable function, the oversized input causes a stack-based buffer overflow that can overwrite critical stack data including return addresses.

The vulnerability manifests when the sub_49E098 function processes the list parameter without proper boundary checks. For detailed technical analysis and proof-of-concept information, refer to the GitHub IoT Vulnerability Report.

Detection Methods for CVE-2025-1853

Indicators of Compromise

• Unusual or malformed HTTP POST requests to /goform/SetIpMacBind with abnormally large list parameters
• Router crashes, reboots, or unresponsive behavior without administrator action
• Unexpected changes to router configuration or settings
• Network traffic anomalies indicating potential backdoor communications originating from the router

Detection Strategies

• Deploy network intrusion detection systems (IDS) with rules monitoring for oversized parameters in HTTP requests to Tenda AC8 management endpoints
• Implement web application firewall (WAF) rules to block requests with excessively long list parameter values
• Monitor router system logs for crash events or memory-related errors in the web management interface

Monitoring Recommendations

• Enable logging on network perimeter devices to capture traffic destined for router management interfaces
• Implement alerting for repeated connection attempts to the /goform/SetIpMacBind endpoint from external or untrusted sources
• Regularly review router access logs for suspicious authentication patterns or management interface access

How to Mitigate CVE-2025-1853

Immediate Actions Required

• Restrict access to the Tenda AC8 web management interface to trusted internal networks only
• Disable remote management features if not required for operations
• Implement network segmentation to isolate IoT devices from critical infrastructure
• Deploy firewall rules blocking external access to router management ports (typically TCP 80/443)

Patch Information

At the time of publication, no official patch from Tenda has been identified in the available references. Administrators should monitor the Tenda Official Website for firmware updates addressing this vulnerability. Until a patch is released, apply the recommended workarounds to reduce exposure.

Workarounds

• Place the router behind a dedicated firewall that filters malicious requests to the management interface
• Use strong, unique credentials for router administration and limit administrative access to specific IP addresses
• Consider replacing affected devices with alternatives that have active security support if no patch becomes available
• Disable unnecessary services and features on the router to minimize attack surface

# Example firewall rule to restrict management access (iptables)
# Block external access to router management interface
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP