CVE-2026-1140: UTT 进取 520W Buffer Overflow RCE Vulnerability

CVE-2026-1140 Overview

A buffer overflow vulnerability has been discovered in the UTT 进取 520W router firmware version 1.7.7-180627. This issue affects the strcpy function within the file /goform/ConfigExceptAli. The vulnerability allows remote attackers to manipulate input data, resulting in a buffer overflow condition that can lead to system compromise. The exploit has been made public and could be actively used in attacks. The vendor was contacted about this disclosure but did not respond.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability to potentially execute arbitrary code, crash the device, or gain unauthorized access to the affected router. Network infrastructure devices like routers are critical targets as they can provide attackers with network-level access.

Affected Products

• UTT 进取 520W Router Firmware Version 1.7.7-180627

Discovery Timeline

• 2026-01-19 - CVE-2026-1140 published to NVD
• 2026-01-19 - Last updated in NVD database

Technical Details for CVE-2026-1140

Vulnerability Analysis

This vulnerability falls under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), a category of memory corruption flaws that occur when software performs operations on a memory buffer without proper boundary checks. The vulnerable code resides in the web management interface endpoint /goform/ConfigExceptAli, which processes user-supplied input using the unsafe strcpy function.

The strcpy function in C copies a source string to a destination buffer without verifying that the destination buffer is large enough to accommodate the source string. When an attacker supplies input data exceeding the expected buffer size, the function will continue writing beyond the allocated memory region, corrupting adjacent memory structures and potentially overwriting critical data such as return addresses or function pointers.

Root Cause

The root cause of this vulnerability is the use of the strcpy function without proper input length validation. This function does not perform bounds checking, making it inherently unsafe for processing untrusted user input. When processing requests to the /goform/ConfigExceptAli endpoint, the firmware fails to validate the length of user-supplied data before copying it into a fixed-size buffer, leading to the buffer overflow condition.

Attack Vector

The attack can be launched remotely over the network against the web management interface of the affected router. An attacker with low-level privileges can send specially crafted HTTP requests to the /goform/ConfigExceptAli endpoint containing oversized input data. The malicious payload triggers the buffer overflow when the vulnerable strcpy function processes the request, potentially allowing the attacker to:

1. Crash the router causing denial of service
2. Overwrite return addresses to redirect execution flow
3. Execute arbitrary code with the privileges of the web server process
4. Gain persistent access to the router's operating system

The vulnerability mechanism involves sending malformed input data to the affected endpoint. The unsafe strcpy function copies this data without bounds checking, allowing memory corruption. For detailed technical analysis and proof-of-concept information, refer to the GitHub CVE Documentation.

Detection Methods for CVE-2026-1140

Indicators of Compromise

• Unusual or malformed HTTP POST requests to /goform/ConfigExceptAli with abnormally long parameter values
• Router crashes, unexpected reboots, or service disruptions without clear cause
• Anomalous network traffic patterns originating from or directed at the router management interface
• Unauthorized configuration changes or new administrative accounts on the router

Detection Strategies

• Deploy network intrusion detection systems (IDS) with signatures for buffer overflow attacks targeting UTT router endpoints
• Monitor web server logs on the router for requests to /goform/ConfigExceptAli with unusually large payloads
• Implement SentinelOne Singularity platform to detect anomalous process behavior and memory corruption attempts on network devices

Monitoring Recommendations

• Enable logging for all HTTP requests to the router's web management interface
• Set up alerts for requests exceeding normal payload sizes to the vulnerable endpoint
• Monitor for unexpected process terminations or restarts on the router
• Implement network traffic analysis to detect exploitation attempts targeting the management interface

How to Mitigate CVE-2026-1140

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management access from untrusted networks, especially the internet
• Place the router behind a firewall that can filter malicious requests
• Consider replacing the affected device with a supported router from a responsive vendor

Patch Information

No patch is currently available for this vulnerability. The vendor (UTT) was contacted about this disclosure but did not respond. Organizations using affected devices should implement compensating controls and consider device replacement as a long-term solution. For additional details, see the VulDB CTI Entry #341731 and VulDB #341731.

Workarounds

• Restrict web management interface access using IP-based access control lists (ACLs)
• Disable the web management interface entirely if not required and use alternative management methods
• Segment the network to isolate the router's management interface from untrusted networks
• Implement a web application firewall (WAF) in front of the management interface to filter malicious requests

# Example: Restrict management interface access via firewall rules
# Block external access to router management port (typically 80/443)
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