CVE-2026-3814: UTT 810G Firmware Buffer Overflow Flaw

CVE-2026-3814 Overview

A critical buffer overflow vulnerability has been discovered in UTT HiPER 810G firmware versions up to 1.7.7-1711. This security flaw affects the strcpy function within the /goform/getOneApConfTempEntry endpoint, allowing remote attackers to trigger a buffer overflow condition. The vulnerability has been publicly disclosed with exploit code available, increasing the risk of active exploitation against unpatched devices.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability to potentially execute arbitrary code, cause denial of service, or compromise the integrity of affected UTT HiPER 810G network devices.

Affected Products

• UTT HiPER 810G Firmware up to version 1.7.7-1711
• UTT 810G Hardware (version 3.0)
• UTT 810G Firmware (all versions through affected release)

Discovery Timeline

• 2026-03-09 - CVE-2026-3814 published to NVD
• 2026-03-10 - Last updated in NVD database

Technical Details for CVE-2026-3814

Vulnerability Analysis

This vulnerability stems from improper bounds checking in the firmware's web management interface. The affected function uses the unsafe strcpy function to copy user-supplied input without validating the length of the input buffer against the destination buffer size. When an attacker sends a specially crafted HTTP request to the /goform/getOneApConfTempEntry endpoint, the vulnerable code copies the malicious payload directly into a fixed-size stack buffer, overwriting adjacent memory regions.

The buffer overflow condition (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer) enables attackers to corrupt stack memory, potentially overwriting return addresses or other critical data structures. This can lead to arbitrary code execution in the context of the web server process running on the device.

Root Cause

The root cause of CVE-2026-3814 is the use of the unsafe strcpy function without proper input length validation. The strcpy function does not perform bounds checking and will copy data until a null terminator is encountered, regardless of the destination buffer size. This classic programming error in the /goform/getOneApConfTempEntry handler allows an attacker to overflow the target buffer with arbitrarily long input data.

Attack Vector

The vulnerability is exploitable remotely over the network. An authenticated attacker with low privileges can send malicious HTTP requests to the device's web management interface targeting the vulnerable endpoint. The attack does not require user interaction and can be automated. Technical details regarding the exploitation method have been documented in the GitHub CVE Vulnerability Report.

The attack flow involves:

1. Accessing the UTT HiPER 810G web management interface
2. Authenticating with low-privilege credentials
3. Sending a crafted request to /goform/getOneApConfTempEntry with an oversized parameter
4. The strcpy function copies the payload beyond buffer boundaries
5. Successful exploitation may result in code execution or device crash

Detection Methods for CVE-2026-3814

Indicators of Compromise

• Unusual or malformed HTTP requests targeting /goform/getOneApConfTempEntry endpoint
• HTTP requests containing abnormally long parameter values in POST data
• Unexpected device reboots or web interface crashes
• Memory corruption errors or segmentation faults in device logs

Detection Strategies

• Deploy network intrusion detection rules to monitor for oversized HTTP parameters targeting UTT device management endpoints
• Implement web application firewall (WAF) rules to block requests with excessively long input values
• Monitor device logs for signs of service crashes or unexpected restarts of the web management process
• Analyze network traffic for patterns consistent with buffer overflow exploitation attempts

Monitoring Recommendations

• Enable comprehensive logging on UTT HiPER 810G devices and forward logs to a centralized SIEM
• Set up alerts for repeated access attempts to the /goform/getOneApConfTempEntry endpoint
• Monitor for anomalous outbound traffic from affected devices that could indicate successful compromise
• Conduct regular firmware integrity checks to detect any unauthorized modifications

How to Mitigate CVE-2026-3814

Immediate Actions Required

• Restrict network access to the UTT HiPER 810G web management interface to trusted IP addresses only
• Implement network segmentation to isolate affected devices from critical network segments
• Disable remote management access if not strictly required
• Monitor for vendor-released firmware updates and apply patches immediately when available

Patch Information

At the time of publication, no official patch has been released by UTT. Organizations should monitor the vendor's official channels and security advisories for firmware updates addressing CVE-2026-3814. Additional technical details are available through VulDB #349780 and the VulDB CTI entry.

Workarounds

• Place affected UTT HiPER 810G devices behind a firewall that blocks external access to the web management interface
• Use access control lists (ACLs) to limit management interface access to specific administrator IP addresses
• Disable the web management interface and use alternative management methods if available
• Consider replacing vulnerable devices with supported alternatives until patches are available

# Example firewall rule to restrict management access (iptables)
# Allow management access only from trusted admin network
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