CVE-2026-4552: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-4552 Overview

A stack-based buffer overflow vulnerability has been identified in the Tenda F453 router firmware version 1.0.0.3. This vulnerability exists in the fromVirtualSer function located within the /goform/VirtualSer component of the Parameters Handler. An attacker can exploit this flaw by sending a specially crafted page argument to trigger memory corruption, potentially leading to remote code execution or denial of service on affected devices.

Critical Impact

This network-accessible vulnerability allows remote attackers with low privileges to compromise the confidentiality, integrity, and availability of Tenda F453 routers. The exploit has been publicly disclosed, increasing the risk of active exploitation in the wild.

Affected Products

• Tenda F453 Firmware version 1.0.0.3

Discovery Timeline

• 2026-03-22 - CVE-2026-4552 published to NVD
• 2026-03-23 - Last updated in NVD database

Technical Details for CVE-2026-4552

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The fromVirtualSer function fails to properly validate the length of user-supplied input in the page parameter before copying it into a fixed-size stack buffer. When an attacker provides an excessively long value for this parameter, the function writes beyond the allocated buffer boundaries, corrupting adjacent stack memory including potentially the return address.

The network-accessible nature of this vulnerability combined with low attack complexity makes it particularly dangerous for exposed Tenda F453 devices. Since authentication requirements are minimal, attackers can leverage this flaw to achieve arbitrary code execution with the privileges of the web server process, which typically runs as root on embedded devices.

Root Cause

The root cause stems from insufficient bounds checking in the fromVirtualSer function when processing the page parameter from HTTP requests to /goform/VirtualSer. The function uses unsafe string copying operations that do not verify the input length against the destination buffer size, allowing memory corruption when oversized input is provided.

Attack Vector

The attack can be executed remotely over the network by sending a malicious HTTP request to the vulnerable endpoint. An attacker would craft a request to /goform/VirtualSer with an oversized page parameter value. The malicious payload would overflow the stack buffer, potentially overwriting the saved return address to redirect execution flow to attacker-controlled code.

The vulnerability is exploited via the following attack flow:

1. The attacker sends an HTTP GET or POST request to /goform/VirtualSer on the target router
2. The request includes a maliciously crafted page parameter with excessive length
3. The fromVirtualSer function processes this input without proper boundary validation
4. Stack memory is corrupted, potentially allowing control of program execution

For detailed technical analysis and proof-of-concept information, refer to the GitHub Vulnerability Documentation.

Detection Methods for CVE-2026-4552

Indicators of Compromise

• Unusual HTTP requests to /goform/VirtualSer with abnormally large page parameter values
• Router crashes, unexpected reboots, or unstable behavior following web interface access
• Unauthorized configuration changes or unexpected network traffic from the router
• Evidence of exploitation attempts in router access logs referencing the VirtualSer endpoint

Detection Strategies

• Implement network intrusion detection rules to identify HTTP requests to /goform/VirtualSer containing oversized parameters
• Monitor router logs for repeated crashes or restarts that may indicate exploitation attempts
• Deploy web application firewall rules to block requests with excessively long parameter values targeting Tenda endpoints
• Conduct regular firmware integrity checks on Tenda F453 devices

Monitoring Recommendations

• Enable and regularly review HTTP access logs on the router if available
• Monitor network traffic for unusual patterns targeting router management interfaces
• Implement alerts for router availability changes that may indicate successful exploitation
• Regularly audit Tenda device firmware versions against known vulnerability databases

How to Mitigate CVE-2026-4552

Immediate Actions Required

• Restrict network access to the router's web management interface to trusted networks only
• Implement firewall rules to block external access to port 80/443 on the router management interface
• Consider disabling remote management features until a patch is available
• Monitor Tenda's official security advisories for firmware updates addressing this vulnerability

Patch Information

At the time of this publication, no official patch from Tenda has been confirmed. Organizations should monitor the Tenda Official Website for firmware updates. The vulnerability details are documented in VulDB #352379 and the VulDB CVE Report.

Workarounds

• Restrict access to the router's web interface to localhost or a dedicated management VLAN
• Implement network segmentation to isolate Tenda F453 devices from untrusted networks
• Use a reverse proxy with input validation to filter requests to vulnerable endpoints
• Consider replacing affected devices with alternative routers if patches are not available

# Example iptables rule to restrict access to router management interface
# Apply on upstream firewall or router if supported

# Block external access to web management port
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

# Log suspicious requests for monitoring
iptables -A INPUT -p tcp --dport 80 -j LOG --log-prefix "TENDA_ACCESS: "