CVE-2026-4862: UTT HiPER 1250GW Buffer Overflow Flaw

CVE-2026-4862 Overview

A buffer overflow vulnerability has been identified in the UTT HiPER 1250GW wireless router affecting firmware versions up to 3.2.7-210907-180535. This issue exists in the strcpy function within the /goform/formConfigDnsFilterGlobal endpoint of the Parameter Handler component. An attacker can exploit this vulnerability by manipulating the GroupName argument to trigger a buffer overflow condition. The attack can be launched remotely by an authenticated user, potentially leading to arbitrary code execution or denial of service on the affected device.

Critical Impact

Remote attackers with low privileges can exploit this buffer overflow to potentially execute arbitrary code, compromise device integrity, or cause system crashes on affected UTT HiPER 1250GW routers.

Affected Products

• UTT HiPER 1250GW firmware versions up to 3.2.7-210907-180535
• Devices using the vulnerable Parameter Handler component
• Systems with exposed /goform/formConfigDnsFilterGlobal endpoint

Discovery Timeline

• March 26, 2026 - CVE-2026-4862 published to NVD
• March 26, 2026 - Last updated in NVD database

Technical Details for CVE-2026-4862

Vulnerability Analysis

This vulnerability stems from improper bounds checking in the DNS Filter Global configuration handler. The affected firmware uses the unsafe strcpy function to copy user-supplied data from the GroupName parameter without validating the input length. When an attacker provides an oversized string value for the GroupName argument, it exceeds the allocated buffer capacity, causing adjacent memory to be overwritten.

The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), which encompasses buffer overflow conditions where input data is not properly validated before memory operations. This type of flaw is particularly dangerous in embedded network devices like routers, as they often run with elevated privileges and may lack modern memory protection mechanisms such as ASLR or stack canaries.

Root Cause

The root cause is the use of the unsafe strcpy function to handle user-controlled input in the /goform/formConfigDnsFilterGlobal endpoint. The strcpy function does not perform bounds checking, copying data until a null terminator is encountered. When the GroupName parameter exceeds the expected buffer size, this results in a classic stack-based or heap-based buffer overflow, depending on the memory allocation strategy used by the firmware.

Attack Vector

The attack vector is network-based, requiring low-level privileges (authenticated access) but no user interaction. An attacker with valid credentials to the router's web management interface can send a specially crafted HTTP POST request to the /goform/formConfigDnsFilterGlobal endpoint containing an oversized GroupName parameter. The exploit has been publicly disclosed, increasing the risk of active exploitation.

The attack flow involves:

1. Authenticating to the router's web interface with valid credentials
2. Crafting an HTTP request to the vulnerable endpoint
3. Supplying an excessively long GroupName value to overflow the buffer
4. Potentially achieving code execution or causing a denial of service

Technical details and proof-of-concept information can be found in the GitHub IOT Vulnerability Report.

Detection Methods for CVE-2026-4862

Indicators of Compromise

• Unexpected router reboots or instability after administrative actions
• Anomalous HTTP POST requests to /goform/formConfigDnsFilterGlobal with unusually large payloads
• Crash logs or memory dump files indicating buffer overflow conditions
• Unauthorized configuration changes to DNS filtering settings

Detection Strategies

• Monitor HTTP traffic to UTT HiPER routers for requests containing excessively long GroupName parameters
• Implement web application firewall rules to detect and block oversized form submissions to vulnerable endpoints
• Deploy network intrusion detection signatures for known exploitation patterns targeting this CVE
• Review router access logs for suspicious authentication patterns followed by configuration changes

Monitoring Recommendations

• Enable comprehensive logging on UTT HiPER 1250GW devices if available
• Monitor for unusual outbound connections from the router that may indicate compromise
• Implement network segmentation to isolate router management interfaces from untrusted networks
• Deploy SentinelOne Singularity for IoT to gain visibility into network device behaviors and detect anomalous activity patterns

How to Mitigate CVE-2026-4862

Immediate Actions Required

• Restrict management interface access to trusted IP addresses only
• Implement strong authentication credentials and consider disabling remote management if not required
• Place UTT HiPER 1250GW devices behind a firewall that can inspect and filter malicious requests
• Monitor vendor communications for firmware updates addressing this vulnerability

Patch Information

At the time of publication, no official patch has been confirmed from UTT. Organizations should monitor the VulDB entry and the vendor's official channels for security updates. The vulnerability affects firmware versions up to 3.2.7-210907-180535, suggesting that a newer firmware version may address this issue when released.

Workarounds

• Disable remote management access and only allow local/console administration
• Implement network access control lists (ACLs) to restrict which hosts can reach the router's management interface
• Consider deploying a reverse proxy or web application firewall in front of the management interface to filter malicious input
• Evaluate replacing affected devices with alternative products if no patch becomes available

# Example: Restrict management interface access using firewall rules
# Block external access to router management port (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

# Alternative: Disable remote management if supported by device CLI
# Consult UTT HiPER documentation for device-specific commands