CVE-2026-6186: UTT HiPER 1200GW Buffer Overflow Flaw

CVE-2026-6186 Overview

A buffer overflow vulnerability has been identified in UTT HiPER 1200GW routers running firmware versions up to 2.5.3-170306. This vulnerability affects the strcpy function within the /goform/formNatStaticMap endpoint, where improper handling of the NatBind argument allows attackers to trigger a buffer overflow condition. The vulnerability can be exploited remotely by authenticated attackers, potentially leading to arbitrary code execution or denial of service.

Critical Impact

Remote attackers with low privileges can exploit this buffer overflow to potentially achieve code execution on affected UTT HiPER 1200GW routers, compromising network infrastructure security.

Affected Products

• UTT HiPER 1200GW firmware version 2.5.3-170306 and earlier
• UTT HiPER 1200GW devices with vulnerable /goform/formNatStaticMap endpoint

Discovery Timeline

• April 13, 2026 - CVE-2026-6186 published to NVD
• April 13, 2026 - Last updated in NVD database

Technical Details for CVE-2026-6186

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw exists in the web management interface of UTT HiPER 1200GW routers, specifically within the NAT static mapping configuration functionality.

The vulnerable endpoint /goform/formNatStaticMap processes user-supplied input through the NatBind parameter without adequate bounds checking. When the strcpy function is called to copy user-controlled data into a fixed-size buffer, an attacker can supply an oversized input string that exceeds the allocated buffer space, overwriting adjacent memory regions.

This type of classic stack-based buffer overflow can corrupt critical memory structures including return addresses and saved registers, potentially allowing an attacker to redirect program execution to malicious shellcode or achieve arbitrary code execution within the router's firmware context.

Root Cause

The root cause is the use of the unsafe strcpy function to handle user-supplied input from the NatBind parameter without proper input validation or length checking. The strcpy function does not perform bounds checking and will continue copying data until it encounters a null terminator, regardless of the destination buffer size. This classic C programming error allows attackers to overflow the buffer by providing input longer than the allocated buffer space.

Attack Vector

The attack can be carried out remotely over the network by sending a specially crafted HTTP request to the vulnerable /goform/formNatStaticMap endpoint. The attacker must have low-level privileges (authenticated access) to the router's web management interface. By manipulating the NatBind parameter with an excessively long string, the attacker can trigger the buffer overflow condition.

The exploit has been publicly disclosed and documented, increasing the risk of exploitation in the wild. Network-attached UTT HiPER 1200GW devices with exposed management interfaces are particularly at risk.

Detection Methods for CVE-2026-6186

Indicators of Compromise

• Unusual HTTP POST requests to /goform/formNatStaticMap with abnormally long NatBind parameter values
• Unexpected router reboots or crashes indicating potential exploitation attempts
• Anomalous memory access patterns or segmentation faults in router logs
• Unauthorized configuration changes to NAT static mapping settings

Detection Strategies

• Implement network-based intrusion detection rules to monitor for oversized HTTP POST requests targeting /goform/formNatStaticMap
• Deploy web application firewall (WAF) rules to block requests with NatBind parameters exceeding expected length thresholds
• Monitor router access logs for repeated authentication attempts followed by requests to the vulnerable endpoint
• Configure alerts for unexpected firmware crashes or service restarts on affected devices

Monitoring Recommendations

• Enable comprehensive logging on UTT HiPER 1200GW devices and forward logs to a centralized SIEM
• Monitor network traffic for anomalous patterns targeting router management interfaces
• Implement baseline monitoring for normal router behavior to detect deviation patterns
• Regularly review access logs for the web management interface for suspicious activity

How to Mitigate CVE-2026-6186

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management access if not required for operations
• Place UTT HiPER 1200GW devices behind a firewall that blocks external access to management ports
• Implement network segmentation to isolate vulnerable devices from untrusted networks
• Monitor for vendor firmware updates that address this vulnerability

Patch Information

As of the publication date, no official patch has been confirmed from the vendor. Organizations should monitor UTT's official channels for security updates. In the interim, apply the workarounds listed below to reduce exposure.

For additional technical details, refer to the GitHub CVE Analysis and VulDB entry #357108.

Workarounds

• Disable the web management interface if not actively required for administration
• Implement access control lists (ACLs) to restrict management interface access to specific trusted IP addresses
• Deploy a VPN requirement for any remote management access to affected devices
• Consider replacing affected devices with alternative products if critical security updates are not forthcoming from the vendor

# Example: Restrict management interface access via firewall rules
# Block external access to management ports (adjust port as needed)
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