CVE-2026-52198: UTT nv518G DoS Vulnerability

CVE-2026-52198 Overview

CVE-2026-52198 is a buffer overflow vulnerability affecting UTT nv518G firmware version nv518GV3v3.2.7-210919-161313. The flaw resides in the gohead/sub_425994 component of the device's web management interface. A remote, unauthenticated attacker can exploit the vulnerability over the network to trigger a denial of service condition on the affected router. The issue is categorized under CWE-120: Buffer Copy without Checking Size of Input.

Critical Impact
Remote unauthenticated attackers can crash the UTT 518G router by sending crafted requests to the vulnerable gohead handler, disrupting network availability for all downstream users.

Affected Products

UTT nv518G router
Firmware version nv518GV3v3.2.7-210919-161313
gohead/sub_425994 web service component

Discovery Timeline

2026-06-30 - CVE-2026-52198 published to NVD
2026-07-02 - Last updated in NVD database

Technical Details for CVE-2026-52198

Vulnerability Analysis

The vulnerability exists in the gohead web server binary running on UTT nv518G devices. Specifically, the function identified as sub_425994 fails to validate the length of attacker-supplied input before copying it into a fixed-size stack or heap buffer. When an oversized value reaches the vulnerable routine, the copy operation writes past the destination boundary and corrupts adjacent memory. This corruption crashes the gohead process and interrupts the router's management and forwarding services.

Because gohead is exposed on the device's network interface and does not require authentication for the affected code path, the attack surface is reachable from any host that can contact the router's management service. Exploitation impacts availability only — the current advisory does not indicate confidentiality or integrity impact.

Root Cause

The root cause is a classic [CWE-120] buffer copy without input size validation. The sub_425994 handler processes an attacker-controlled field without enforcing an upper bound against the destination buffer size. Embedded routers frequently rely on unsafe C string primitives such as strcpy, sprintf, or memcpy with attacker-controlled length parameters, and the referenced GitHub CVE Report documents the offset and function pointer disassembly for this specific case.

Attack Vector

Exploitation requires network access to the router's web management interface. The attacker crafts an HTTP request containing an oversized parameter targeting the endpoint dispatched to sub_425994. No credentials, user interaction, or prior foothold are required. On receipt, the vulnerable process dereferences corrupted memory and terminates, producing a denial of service. See the GitHub CVE Report for the request layout and reversed function details.

Detection Methods for CVE-2026-52198

Indicators of Compromise

Unexpected restarts or crash loops of the gohead process on UTT nv518G routers.
Loss of management interface availability following inbound HTTP requests from untrusted sources.
HTTP requests to the router containing abnormally long query string or POST body parameters.

Detection Strategies

Inspect network traffic to router management interfaces for HTTP requests with oversized fields targeting gohead endpoints.
Correlate router availability drops with inbound requests logged by upstream firewalls or IDS sensors.
Deploy IDS signatures that flag HTTP requests exceeding expected parameter length limits toward embedded management interfaces.

Monitoring Recommendations

Forward router syslog and crash telemetry to a centralized log platform to detect repeated gohead failures.
Monitor uplink and LAN interfaces for sudden loss of gateway reachability, which may indicate exploitation.
Alert on any external source attempting to reach the router's HTTP management port.

How to Mitigate CVE-2026-52198

Immediate Actions Required

Restrict access to the router's web management interface to trusted management VLANs or specific administrator IP addresses.
Disable remote WAN-side administration on affected UTT nv518G devices.
Inventory all UTT 518G devices running firmware nv518GV3v3.2.7-210919-161313 and prioritize remediation for internet-exposed units.

Patch Information

As of publication, no vendor patch is referenced in the NVD entry for CVE-2026-52198. Administrators should monitor the UTT Download Center for updated firmware addressing the sub_425994 handler and apply it as soon as it becomes available.

Workarounds

Place the router's management interface behind a firewall rule permitting access only from a management jump host.
Segment untrusted networks from the router's administrative interface using VLAN isolation.
If remote management is not required, disable the HTTP administration service entirely until a fixed firmware release is available.

bash

# Example ACL restricting router management access to a trusted admin subnet
# Replace 10.0.0.0/24 with your management network
access-list MGMT permit tcp 10.0.0.0/24 host <router-ip> eq 80
access-list MGMT deny   tcp any host <router-ip> eq 80
access-list MGMT permit ip any any