CVE-2025-4299: Tenda AC1206 Buffer Overflow Vulnerability

CVE-2025-4299 Overview

A critical buffer overflow vulnerability has been identified in Tenda AC1206 wireless routers running firmware versions up to 15.03.06.23. The vulnerability exists within the setSchedWifi function located in the /goform/openSchedWifi endpoint. Improper input validation allows attackers to overflow memory buffers, potentially leading to remote code execution or device compromise.

This vulnerability is particularly concerning as it can be exploited remotely over the network by authenticated attackers. The exploit details have been publicly disclosed, increasing the risk of active exploitation in the wild.

Critical Impact

Remote attackers with low privileges can exploit this buffer overflow to achieve high impact on confidentiality, integrity, and availability of affected Tenda AC1206 routers, potentially gaining full control of the device.

Affected Products

• Tenda AC1206 Firmware (versions up to 15.03.06.23)
• Tenda AC1206 Hardware Device

Discovery Timeline

• 2025-05-06 - CVE-2025-4299 published to NVD
• 2025-05-13 - Last updated in NVD database

Technical Details for CVE-2025-4299

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-120 (Buffer Copy without Checking Size of Input). The setSchedWifi function in the Tenda AC1206 firmware fails to properly validate the size of user-supplied input before copying it into a fixed-size buffer.

When processing requests to the /goform/openSchedWifi endpoint, the firmware does not enforce proper bounds checking on incoming data. This allows an attacker to supply input that exceeds the allocated buffer size, overwriting adjacent memory regions. Depending on the memory layout and exploitation technique, this could enable arbitrary code execution, denial of service, or device takeover.

The network-accessible nature of this vulnerability combined with the low complexity required for exploitation makes it a significant threat to affected devices. Attackers with even low-level privileges can initiate the attack remotely without any user interaction required.

Root Cause

The root cause of this vulnerability is insufficient input validation within the setSchedWifi function. The function processes WiFi scheduling configuration parameters without verifying that the supplied data fits within the expected buffer boundaries. This classic buffer overflow pattern allows memory corruption when oversized input is provided.

The firmware lacks proper bounds checking mechanisms that would prevent buffer overflows, a common issue in embedded device firmware where memory-safe programming practices may not be consistently applied.

Attack Vector

The attack can be initiated remotely over the network by sending specially crafted HTTP requests to the /goform/openSchedWifi endpoint. An authenticated attacker with low privileges can manipulate the input parameters to trigger the buffer overflow condition.

The attack flow involves:

1. Authenticating to the router's web management interface with low-level credentials
2. Sending a malicious request to the /goform/openSchedWifi endpoint with oversized parameter values
3. The setSchedWifi function copies the malicious input into a fixed-size buffer without proper bounds checking
4. The buffer overflow occurs, potentially overwriting critical memory regions including return addresses or function pointers

Technical details regarding the specific exploitation methodology can be found in the GitHub Documentation for WiFi Scheduling.

Detection Methods for CVE-2025-4299

Indicators of Compromise

• Unusual HTTP POST requests to /goform/openSchedWifi containing abnormally large parameter values
• Router crashes, reboots, or unresponsive behavior following web interface access
• Unexpected configuration changes to WiFi scheduling settings
• Anomalous network traffic originating from the router to unknown external destinations

Detection Strategies

• Monitor HTTP traffic to the router's management interface for requests to /goform/openSchedWifi with oversized payloads
• Implement network intrusion detection rules to identify buffer overflow patterns in router management traffic
• Deploy SentinelOne Singularity to detect anomalous behavior patterns on network segments containing vulnerable Tenda devices
• Review router access logs for suspicious authentication attempts followed by configuration changes

Monitoring Recommendations

• Enable logging on the router management interface and centralize logs for analysis
• Monitor for unusual patterns in WiFi scheduling configuration changes
• Implement network segmentation to isolate IoT and networking devices from critical infrastructure
• Establish baseline traffic patterns to identify anomalous requests targeting router endpoints

How to Mitigate CVE-2025-4299

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management access if not required for operations
• Implement network segmentation to limit exposure of vulnerable devices
• Monitor for exploitation attempts using network intrusion detection systems
• Consider replacing affected devices with models from vendors with better security patching practices

Patch Information

At the time of publication, no official patch has been released by Tenda for this vulnerability. Organizations should monitor the Tenda Official Website for firmware updates. Given the public disclosure of exploit details, applying patches immediately upon availability is critical.

For tracking and additional vulnerability details, refer to VulDB #307403.

Workarounds

• Restrict management interface access to local network only by disabling WAN-side management
• Implement strong authentication credentials to reduce the risk of unauthorized access
• Place vulnerable routers behind a firewall or VPN to limit network exposure
• Use access control lists (ACLs) to restrict which devices can communicate with the router's management interface
• Consider deploying a network monitoring solution to detect and alert on exploitation attempts

# Example: Restrict management access via iptables on upstream device
# Block external access to the router's management port
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 specific management station
iptables -I FORWARD -s <ADMIN_IP> -d <ROUTER_IP> -p tcp --dport 80 -j ACCEPT