CVE-2026-3273: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-3273 Overview

A buffer overflow vulnerability has been identified in the Tenda F453 router firmware version 1.0.0.3. This vulnerability affects the formWrlsafeset function within the /goform/AdvSetWrlsafeset endpoint of the httpd component. Improper handling of the mit_ssid_index argument allows attackers to trigger a buffer overflow condition, potentially enabling remote code execution or denial of service on affected devices.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability over the network to compromise Tenda F453 routers, potentially gaining unauthorized access to network infrastructure or disrupting router operations.

Affected Products

• Tenda F453 Firmware version 1.0.0.3
• Tenda F453 Hardware

Discovery Timeline

• 2026-02-27 - CVE-2026-3273 published to NVD
• 2026-02-27 - Last updated in NVD database

Technical Details for CVE-2026-3273

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the httpd service running on the Tenda F453 router, specifically within the formWrlsafeset function that handles wireless security configuration requests.

When processing HTTP requests to the /goform/AdvSetWrlsafeset endpoint, the function fails to properly validate the length or content of the mit_ssid_index parameter before copying it into a fixed-size buffer. This lack of bounds checking allows an attacker to supply oversized input that overflows the destination buffer, potentially overwriting adjacent memory regions including return addresses or function pointers.

The vulnerability can be exploited remotely over the network by any authenticated user with access to the router's web management interface. Successful exploitation could lead to arbitrary code execution with the privileges of the httpd process, complete device compromise, or denial of service through system crashes.

Root Cause

The root cause of this vulnerability is insufficient input validation in the formWrlsafeset function. The function processes the mit_ssid_index parameter from user-supplied HTTP POST data without verifying that the input length does not exceed the allocated buffer size. This is a classic buffer overflow pattern where developer oversight in boundary checking leads to memory corruption vulnerabilities.

Attack Vector

The attack can be executed remotely over the network. An attacker with network access to the Tenda F453 router's web interface can craft a malicious HTTP request to the /goform/AdvSetWrlsafeset endpoint. By manipulating the mit_ssid_index parameter with specially crafted data exceeding expected bounds, the attacker can overflow the target buffer and potentially hijack program execution flow.

The vulnerability is accessible through the router's httpd service, which typically listens on port 80 (HTTP) or 443 (HTTPS) on the local network interface. If remote management is enabled, this attack surface may also be exposed to the internet.

Detection Methods for CVE-2026-3273

Indicators of Compromise

• Unusual HTTP POST requests to /goform/AdvSetWrlsafeset with abnormally large mit_ssid_index parameter values
• Router crashes or unexpected reboots following web management access
• Suspicious outbound network connections from the router to unknown IP addresses
• Unauthorized configuration changes to wireless security settings

Detection Strategies

• Monitor HTTP traffic to Tenda F453 routers for requests containing oversized parameters in the /goform/AdvSetWrlsafeset endpoint
• Deploy network intrusion detection signatures to identify buffer overflow exploitation patterns targeting Tenda router firmware
• Implement log analysis to detect repeated failed authentication attempts followed by exploitation attempts
• Use firmware integrity checking to identify unauthorized modifications to router software

Monitoring Recommendations

• Enable logging on network firewalls to capture all traffic destined for router management interfaces
• Configure SIEM alerts for anomalous HTTP request patterns targeting embedded device management endpoints
• Regularly audit router configurations for unauthorized changes that may indicate successful exploitation
• Monitor for unexpected router behavior including performance degradation or connectivity issues

How to Mitigate CVE-2026-3273

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
• Implement network segmentation to isolate vulnerable devices from untrusted network segments
• Monitor for exploitation attempts using network security tools

Patch Information

At the time of publication, no vendor patch has been confirmed for this vulnerability. Users should monitor the Tenda Official Website for firmware updates addressing this issue. Additional technical details about this vulnerability can be found in the GitHub Vulnerability Database Entry and the VulDB CVE Analysis.

Workarounds

• Configure firewall rules to block external access to port 80/443 on the router's management interface
• Use a VPN to access router management functions rather than exposing the web interface directly
• Consider replacing affected devices with alternative hardware if patches are not made available
• Implement strong authentication and regularly rotate credentials for router access

# Example firewall rule to restrict management interface access
# 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