CVE-2026-4318: UTT HiPER 810G Buffer Overflow Vulnerability

CVE-2026-4318 Overview

A buffer overflow vulnerability has been identified in UTT HiPER 810G routers running firmware versions up to 1.7.7-171114. The vulnerability affects the strcpy function in the file /goform/formApLbConfig, where improper handling of the loadBalanceNameOld argument allows an attacker to trigger a buffer overflow condition. This vulnerability can be exploited remotely by authenticated attackers to potentially execute arbitrary code or cause denial of service on affected devices.

Critical Impact

Remote attackers with low privileges can exploit this buffer overflow vulnerability to potentially achieve full control over affected UTT HiPER 810G routers, compromising network security and enabling further attacks on connected infrastructure.

Affected Products

• UTT HiPER 810G firmware up to version 1.7.7-171114
• UTT HiPER 810G routers with web management interface enabled
• Network environments utilizing affected UTT router appliances

Discovery Timeline

• 2026-03-17 - CVE-2026-4318 published to NVD
• 2026-03-18 - Last updated in NVD database

Technical Details for CVE-2026-4318

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw exists in the load balancing configuration handler of the UTT HiPER 810G router's web management interface.

The vulnerable endpoint /goform/formApLbConfig processes load balancing configuration requests without properly validating the length of user-supplied input in the loadBalanceNameOld parameter. The use of the unsafe strcpy function to handle this parameter creates a classic stack-based buffer overflow condition.

When an attacker supplies an overly long string to the loadBalanceNameOld parameter, the strcpy function copies the data without bounds checking, potentially overwriting adjacent memory including the return address on the stack. This can lead to arbitrary code execution within the context of the web server process running on the router.

The exploit has been publicly disclosed, increasing the urgency for organizations to apply mitigations. The network-accessible nature of the vulnerability means attackers can target these devices from anywhere with network connectivity to the management interface.

Root Cause

The root cause of CVE-2026-4318 is the improper use of the strcpy function without adequate input length validation. The strcpy function does not perform bounds checking, making it inherently dangerous when used with user-controlled input. The developers failed to implement proper input sanitization or use safer alternatives such as strncpy or strlcpy that enforce buffer size limits.

Attack Vector

The attack can be initiated remotely over the network. An attacker with low-level privileges (authenticated access to the router's web interface) can craft a malicious HTTP request to the /goform/formApLbConfig endpoint. By including an excessively long string in the loadBalanceNameOld parameter, the attacker triggers the buffer overflow condition.

The vulnerability is accessible through the router's web management interface, typically exposed on the local network and potentially on the WAN interface if remote management is enabled. For more technical details on the exploitation method, refer to the GitHub Issue Tracker where the vulnerability was publicly disclosed.

Detection Methods for CVE-2026-4318

Indicators of Compromise

• Anomalous HTTP POST requests to /goform/formApLbConfig containing unusually long loadBalanceNameOld parameter values
• Router crashes or unexpected reboots following web interface access
• Unexpected modifications to load balancing configurations
• Unusual network traffic patterns originating from the router management interface

Detection Strategies

• Implement web application firewall rules to detect and block HTTP requests with excessively long parameter values targeting UTT router endpoints
• Monitor network traffic for requests to /goform/formApLbConfig with abnormally sized payloads exceeding normal configuration string lengths
• Deploy intrusion detection signatures that identify buffer overflow attack patterns against UTT HiPER devices
• Enable verbose logging on network perimeter devices to capture attempts to reach router management interfaces

Monitoring Recommendations

• Regularly review router access logs for suspicious authentication attempts and configuration changes
• Implement network segmentation to isolate router management interfaces from untrusted network segments
• Configure SIEM alerts for multiple failed authentication attempts followed by successful access to router administration pages
• Monitor for any process crashes or abnormal behavior on UTT HiPER 810G devices

How to Mitigate CVE-2026-4318

Immediate Actions Required

• Restrict access to the router web management interface to trusted IP addresses only using firewall rules
• Disable remote management features if not explicitly required for operations
• Implement strong authentication credentials for all router administrative accounts
• Place affected routers behind a VPN or jump host to limit exposure

Patch Information

No official patch information has been provided by UTT at the time of publication. Organizations should monitor for firmware updates from the vendor. Additional vulnerability details can be found at VulDB #351362 and the VulDB Submission #772659.

Workarounds

• Configure access control lists (ACLs) to restrict management interface access to specific trusted administrator IP addresses
• Disable the web management interface entirely if command-line administration is sufficient for operational needs
• Implement network-level firewalling to block external access to the router's management ports
• Consider replacing vulnerable devices with alternative hardware if vendor patches are not forthcoming

# Example ACL configuration to restrict management access
# Apply to router WAN interface to block external management access
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP