CVE-2026-5990 Overview
A stack-based buffer overflow vulnerability has been identified in the Tenda F451 router firmware version 1.0.0.7. The vulnerability exists in the fromSafeEmailFilter function located in the /goform/SafeEmailFilter endpoint. Improper handling of the page argument allows an authenticated attacker to trigger a stack-based buffer overflow, potentially leading to remote code execution or denial of service on the affected device.
Critical Impact
Remote attackers with low privileges can exploit this buffer overflow vulnerability to achieve arbitrary code execution or crash the router, compromising network security and availability.
Affected Products
- Tenda F451 firmware version 1.0.0.7
- Tenda F451 routers running vulnerable firmware builds
Discovery Timeline
- April 10, 2026 - CVE-2026-5990 published to NVD
- April 13, 2026 - Last updated in NVD database
Technical Details for CVE-2026-5990
Vulnerability Analysis
This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The fromSafeEmailFilter function in the Tenda F451 router firmware fails to properly validate the length of user-supplied input through the page parameter before copying it into a fixed-size stack buffer.
When an attacker sends a crafted HTTP request to the /goform/SafeEmailFilter endpoint with an overly long page parameter value, the function writes beyond the allocated stack buffer boundaries. This memory corruption can overwrite critical stack data including the return address, potentially allowing an attacker to redirect program execution to malicious code.
The vulnerability can be triggered remotely over the network, though it requires low-level authentication to access the affected endpoint. The exploit has been publicly disclosed, increasing the risk of widespread exploitation against unpatched devices.
Root Cause
The root cause stems from insufficient input validation in the fromSafeEmailFilter function. The firmware fails to perform proper bounds checking on the page parameter before using it in memory operations. This is a common vulnerability pattern in embedded device firmware where string handling functions do not enforce size limits, leading to classic stack-based buffer overflow conditions.
Attack Vector
The attack vector is network-based, requiring the attacker to send specially crafted HTTP requests to the router's web management interface. The attacker must have low-level authentication credentials to access the /goform/SafeEmailFilter endpoint. Once authenticated, the attacker can submit a malicious request containing an oversized page parameter value designed to overflow the stack buffer and potentially gain control of program execution.
The vulnerability can be exploited by sending a POST request to the /goform/SafeEmailFilter endpoint with a page parameter containing carefully crafted data to overflow the stack buffer. Technical details of the exploitation methodology are available in the GitHub Issue Discussion where the vulnerability was publicly disclosed.
Detection Methods for CVE-2026-5990
Indicators of Compromise
- Unusual HTTP POST requests to /goform/SafeEmailFilter with abnormally long page parameter values
- Router crashes or unexpected reboots without user intervention
- Unexpected outbound network connections originating from the router
- Modified router configuration or unauthorized administrative access
Detection Strategies
- Monitor HTTP traffic to router management interfaces for requests containing excessively long parameter values
- Implement intrusion detection rules to alert on POST requests to /goform/SafeEmailFilter with payload sizes exceeding normal thresholds
- Deploy network anomaly detection to identify unusual traffic patterns targeting router administrative endpoints
- Review router logs for repeated access attempts to the SafeEmailFilter endpoint
Monitoring Recommendations
- Restrict management interface access to trusted networks and IP addresses only
- Enable logging on the router's web management interface if supported
- Monitor for firmware integrity changes using hash verification
- Set up alerts for router connectivity issues that may indicate exploitation attempts
How to Mitigate CVE-2026-5990
Immediate Actions Required
- Disable remote management access to the router's web interface immediately
- Restrict access to the router's administrative interface to trusted internal networks only
- Implement firewall rules to block external access to the router management ports
- Monitor for firmware updates from Tenda and apply patches as soon as available
Patch Information
No official patch information is currently available from Tenda. Users should monitor the Tenda Official Website for firmware updates addressing this vulnerability. Additional technical details and vulnerability tracking information can be found at VulDB Vulnerability #356544.
Workarounds
- Disable the web management interface entirely if not required for operations
- Implement network segmentation to isolate IoT and network devices from critical systems
- Use a VPN or jump host for administrative access rather than exposing the management interface directly
- Consider replacing affected devices with alternatives that have active security support
# Configuration example - Firewall rules to block external access to router management
# Block external access to common router management ports
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
iptables -A INPUT -p tcp --dport 8080 -s ! 192.168.1.0/24 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
