CVE-2026-5989: Tenda F451 Buffer Overflow Vulnerability

CVE-2026-5989 Overview

A stack-based buffer overflow vulnerability has been identified in Tenda F451 firmware version 1.0.0.7. The flaw exists in the fromRouteStatic function located in the /goform/RouteStatic file. By manipulating the page argument, an attacker can trigger a stack-based buffer overflow condition. This vulnerability can be exploited remotely without user interaction, making it a significant threat to affected network devices. The exploit has been publicly disclosed and may be actively used in attacks.

Critical Impact

Remote attackers can exploit this stack-based buffer overflow to potentially execute arbitrary code or cause denial of service on Tenda F451 routers, compromising network security and integrity.

Affected Products

• Tenda F451 firmware version 1.0.0.7

Discovery Timeline

• April 10, 2026 - CVE-2026-5989 published to NVD
• April 13, 2026 - Last updated in NVD database

Technical Details for CVE-2026-5989

Vulnerability Analysis

This vulnerability affects the fromRouteStatic function in the Tenda F451 router firmware. The function processes routing configuration requests through the web management interface at /goform/RouteStatic. When handling the page parameter, the function fails to properly validate the length of user-supplied input before copying it into a fixed-size stack buffer.

The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), which encompasses various buffer boundary issues. Stack-based buffer overflows are particularly dangerous in embedded devices like routers, as they often lack modern memory protection mechanisms such as ASLR (Address Space Layout Randomization) or stack canaries.

Successful exploitation could allow an authenticated attacker to overwrite adjacent stack memory, potentially including the return address. This could lead to arbitrary code execution with the privileges of the web server process, or denial of service through application crash.

Root Cause

The root cause of this vulnerability is improper input validation in the fromRouteStatic function. The code fails to enforce proper boundary checks when processing the page argument, allowing an attacker to supply an overly long string that exceeds the allocated buffer size. This is a classic example of unsafe memory handling in C/C++ code where user-controlled input is copied to a fixed-size buffer without length verification.

Attack Vector

The attack can be launched remotely over the network. An attacker with low-privilege access to the router's web management interface can craft a malicious HTTP request to /goform/RouteStatic with an oversized page parameter. When the fromRouteStatic function processes this request, the buffer overflow is triggered.

The network-based attack vector combined with low attack complexity makes this vulnerability particularly concerning for devices exposed on local networks or, in misconfigured environments, accessible from the internet.

Technical details and proof-of-concept information have been documented in external references. For detailed exploitation mechanics, refer to the GitHub Issue Report and VulDB entry #356543.

Detection Methods for CVE-2026-5989

Indicators of Compromise

• Unexpected crashes or reboots of Tenda F451 routers
• Anomalous HTTP POST requests to /goform/RouteStatic with unusually long page parameter values
• Web server error logs showing memory corruption or segmentation faults related to routing configuration endpoints
• Unusual network traffic patterns originating from the router device

Detection Strategies

• Implement network monitoring to detect HTTP requests to /goform/RouteStatic containing abnormally long parameter values (exceeding expected bounds)
• Deploy intrusion detection signatures to identify buffer overflow exploitation attempts targeting Tenda router web interfaces
• Monitor router device behavior for unexpected service restarts or configuration changes

Monitoring Recommendations

• Enable logging on network firewalls to capture traffic destined for router management interfaces
• Set up alerts for repeated authentication attempts followed by unusual POST requests to goform endpoints
• Conduct regular firmware integrity checks on affected devices to detect potential compromise

How to Mitigate CVE-2026-5989

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management features if not required for operations
• Segment the network to isolate affected Tenda F451 devices from untrusted network segments
• Monitor for firmware updates from Tenda that address this vulnerability

Patch Information

At the time of publication, no official patch has been released by Tenda for this vulnerability. Users should regularly check the Tenda Official Website for security updates and firmware releases. Consider contacting Tenda support directly for guidance on remediation options.

Workarounds

• Configure firewall rules to block external access to the router's web management interface (typically port 80/443)
• Implement network-level access controls to restrict who can reach the /goform/RouteStatic endpoint
• Use a VPN to access the management interface rather than exposing it directly to untrusted networks
• Consider replacing the affected device with an alternative router that has active security support if no patch becomes available

# Example firewall rule to restrict access to router management interface
# Block external access to router management ports
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