CVE-2026-1137: UTT 520W Buffer Overflow Vulnerability

CVE-2026-1137 Overview

A critical buffer overflow vulnerability has been identified in UTT 进取 520W router firmware version 1.7.7-180627. This vulnerability exists in the strcpy function within the file /goform/formWebAuthGlobalConfig, allowing remote attackers to trigger a buffer overflow condition through manipulated input. The exploit has been publicly disclosed, and the vendor was contacted but did not respond to responsible disclosure efforts.

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 UTT router. The attack requires low privileges and can be performed over the network without user interaction.

Affected Products

• UTT 进取 520W firmware version 1.7.7-180627

Discovery Timeline

• 2026-01-19 - CVE CVE-2026-1137 published to NVD
• 2026-01-19 - Last updated in NVD database

Technical Details for CVE-2026-1137

Vulnerability Analysis

This buffer overflow vulnerability (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer) occurs in the UTT 进取 520W router's web authentication configuration handler. The vulnerable code resides in the /goform/formWebAuthGlobalConfig endpoint, which processes user-supplied input without proper bounds checking.

The unsafe use of the strcpy function allows attackers to provide input that exceeds the allocated buffer size, leading to memory corruption. This type of vulnerability is particularly dangerous on embedded network devices like routers, as successful exploitation can lead to complete device compromise, denial of service, or remote code execution depending on the specific memory layout and exploitation techniques employed.

Root Cause

The root cause of this vulnerability is the use of the unsafe strcpy function to copy user-controlled data into a fixed-size buffer without validating the input length. The strcpy function does not perform bounds checking, meaning it will continue copying data until it encounters a null terminator, regardless of the destination buffer's capacity. When input exceeds the buffer size, adjacent memory is overwritten, potentially corrupting critical data structures or control flow information.

Attack Vector

The vulnerability can be exploited remotely over the network. An authenticated attacker with low privileges can send specially crafted HTTP requests to the /goform/formWebAuthGlobalConfig endpoint containing oversized input parameters. The attack does not require user interaction and can be executed directly against exposed router management interfaces.

The attack scenario typically involves:

1. Identifying a UTT 进取 520W router with firmware version 1.7.7-180627
2. Authenticating to the web management interface with minimal privileges
3. Sending a malicious POST request to /goform/formWebAuthGlobalConfig with an oversized payload
4. The strcpy function copies the payload beyond buffer boundaries, causing memory corruption

Since the exploit is publicly available, organizations using affected devices should treat this as an actively exploitable vulnerability. For technical details on the vulnerability mechanics, refer to the GitHub CVE Details.

Detection Methods for CVE-2026-1137

Indicators of Compromise

• Unexpected router crashes or reboots without administrative action
• Unusual HTTP POST requests to /goform/formWebAuthGlobalConfig with abnormally large payloads
• Suspicious network traffic patterns indicating exploitation attempts against the router management interface
• Log entries showing repeated failed or successful authentication attempts followed by configuration changes

Detection Strategies

• Deploy network intrusion detection rules to identify HTTP requests targeting /goform/formWebAuthGlobalConfig with oversized parameters
• Monitor router device logs for anomalous behavior or unexpected service restarts
• Implement web application firewall (WAF) rules to block requests with excessively long input fields to router management endpoints
• Use vulnerability scanning tools to identify exposed UTT 进取 520W devices running vulnerable firmware versions

Monitoring Recommendations

• Enable detailed logging on router management interfaces and centralize logs for analysis
• Set up alerts for any access attempts to the vulnerable endpoint from untrusted networks
• Conduct regular firmware version audits to identify devices running 1.7.7-180627
• Monitor network segments for lateral movement following potential router compromise

How to Mitigate CVE-2026-1137

Immediate Actions Required

• Restrict network access to the router management interface to trusted administrator networks only
• Implement firewall rules to block external access to the /goform/formWebAuthGlobalConfig endpoint
• Consider taking affected devices offline if they are exposed to untrusted networks
• Evaluate replacement options with devices from vendors that provide timely security updates

Patch Information

No patch is currently available from the vendor. The vendor was contacted regarding this vulnerability but did not respond to the disclosure. Organizations should pursue alternative mitigation strategies or consider replacing the affected device with a supported alternative.

For additional technical information, see VulDB #341728 and VulDB CTI ID #341728.

Workarounds

• Disable remote management access to the router and only allow local console administration
• Place the router behind a firewall that blocks access to the web management interface from external networks
• Implement network segmentation to limit the impact of potential router compromise
• Deploy an intrusion prevention system (IPS) with signatures for buffer overflow attacks targeting embedded devices

# Example firewall rule to block external access to management interface
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