CVE-2026-3377: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-3377 Overview

A buffer overflow vulnerability has been identified in Tenda F453 firmware version 1.0.0.3. The vulnerability exists in the fromSafeUrlFilter function within the /goform/SafeUrlFilter endpoint. An attacker can exploit this flaw by manipulating the page argument, resulting in a buffer overflow condition. This vulnerability is remotely exploitable, and a public exploit is available, increasing the risk of active exploitation against unpatched devices.

Critical Impact

Remote attackers with low-privilege access can achieve high-impact compromise of confidentiality, integrity, and availability on affected Tenda F453 routers through buffer overflow exploitation.

Affected Products

• Tenda F453 Firmware version 1.0.0.3
• Tenda F453 Hardware

Discovery Timeline

• 2026-03-01 - CVE-2026-3377 published to NVD
• 2026-03-03 - Last updated in NVD database

Technical Details for CVE-2026-3377

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The fromSafeUrlFilter function fails to properly validate the length of user-supplied input in the page parameter before copying it to a fixed-size buffer. When an attacker submits a specially crafted request with an oversized page value, the function writes beyond the allocated buffer boundaries.

The network-accessible nature of this vulnerability allows remote attackers to target the device without physical access. The low attack complexity combined with the absence of user interaction requirements makes this vulnerability particularly dangerous for exposed devices. Successful exploitation can lead to complete compromise of device confidentiality, integrity, and availability.

Root Cause

The root cause stems from insufficient bounds checking in the fromSafeUrlFilter function when processing the page argument from HTTP requests to /goform/SafeUrlFilter. The function uses unsafe string operations that do not verify input length against the destination buffer size, allowing heap or stack corruption depending on the memory allocation strategy employed by the firmware.

Attack Vector

The attack is initiated remotely via the network by sending malicious HTTP requests to the /goform/SafeUrlFilter endpoint. The attacker must have low-privilege access to the device's web management interface. By crafting a request with an excessively long page parameter value, the attacker can overflow the buffer and potentially:

1. Overwrite adjacent memory structures to corrupt program state
2. Hijack control flow by overwriting return addresses or function pointers
3. Achieve arbitrary code execution on the embedded device
4. Cause denial of service through memory corruption crashes

The vulnerability mechanism involves sending an HTTP POST or GET request to the /goform/SafeUrlFilter endpoint with an oversized page parameter. The fromSafeUrlFilter function processes this input without proper length validation, leading to buffer overflow. Technical details and proof-of-concept information are documented in the GitHub Vulnerability Documentation.

Detection Methods for CVE-2026-3377

Indicators of Compromise

• Abnormally long HTTP request parameters targeting /goform/SafeUrlFilter endpoint
• Unexpected device crashes or reboots indicating memory corruption
• Anomalous network traffic patterns to the router's web management port
• Suspicious modifications to device configuration or firmware

Detection Strategies

• Monitor HTTP traffic for requests to /goform/SafeUrlFilter with unusually long page parameter values
• Implement intrusion detection rules to flag buffer overflow attack patterns against Tenda devices
• Deploy network segmentation to isolate IoT devices and monitor cross-segment traffic
• Enable logging on network firewalls to capture attempts to access router management interfaces from untrusted networks

Monitoring Recommendations

• Implement network-level monitoring for unusual traffic volumes to router management ports
• Deploy signature-based detection for known Tenda exploitation patterns
• Configure alerts for repeated authentication attempts or web interface access from external IPs
• Regularly audit device logs for signs of exploitation attempts or unauthorized access

How to Mitigate CVE-2026-3377

Immediate Actions Required

• Restrict access to the device's web management interface to trusted internal networks only
• Disable remote management features if not required for operational purposes
• Implement firewall rules to block external access to the router's administrative ports
• Monitor for any suspicious activity targeting the device while awaiting vendor patches

Patch Information

At the time of publication, no vendor patch has been released for this vulnerability. Organizations should monitor the Tenda Official Website for firmware updates addressing CVE-2026-3377. Additional vulnerability information is available via VulDB #348262.

Workarounds

• Implement network access control lists (ACLs) to restrict management interface access to authorized IP addresses only
• Place affected devices behind a firewall with strict ingress filtering
• Consider replacing vulnerable devices with alternative hardware if patches are not forthcoming
• Use VPN connections for remote management instead of exposing the web interface directly

# Example firewall rules to restrict management access (adjust for your environment)
# Block external access to router 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