CVE-2026-52191: UTT nv518G Buffer Overflow Denial of Service Vulnerability

Technical summary

This is a classic buffer overflow (CWE-120) affecting the gohead HTTP server subsystem within UTT nv518G network equipment. The vulnerability permits an unauthenticated remote attacker to send a specially crafted request that overflows a fixed-size buffer in the sub_444C8C function, leading to uncontrolled memory corruption and denial of service. The attack vector is network-based with low complexity and no privilege escalation required.

Business impact

Organizations deploying UTT nv518G devices in production environments face service disruption risk. If these devices function as network appliances, gateways, or management interfaces, a remote denial-of-service attack could interrupt critical communications, degrade network availability, and trigger incident response costs. The risk is heightened in environments where UTT devices serve redundancy or load-balancing roles without failover protection.

Affected systems

UTT nv518G devices running firmware version nv518GV3v3.2.7-210919-161313 are affected. Organizations should inventory UTT nv518G deployments and verify firmware versions to determine exposure. The vulnerability does not appear in the CISA Known Exploited Vulnerabilities catalog, but this does not imply the vulnerability is unexploitable or low-risk in production settings.

Exploitability

Exploitation is straightforward from a technical perspective: the flaw requires only network access and can be triggered with a single malformed HTTP request. No authentication, user interaction, or advanced exploitation techniques are necessary. The low attack complexity and network accessibility make this vulnerability practical to exploit, though the impact is limited to denial of service rather than code execution or data compromise.

Remediation

Verify your UTT nv518G firmware version immediately. If running nv518GV3v3.2.7-210919-161313 or other potentially affected versions, check the UTT vendor advisory for patched firmware releases. Once a patch is available, schedule a firmware update during a maintenance window. In the interim, consider isolating or restricting network access to affected devices through firewall rules or VLAN segmentation to limit exposure to untrusted networks.

Patch guidance

Contact UTT for confirmation of available security patches and the process to upgrade nv518G firmware safely. Verify patch availability through the vendor advisory rather than assuming a fix is released. If your devices support it, enable automatic security updates or schedule manual updates on a regular cadence. Test patches in a non-production environment first, as firmware updates may require device downtime or affect existing configurations.

Detection guidance

Monitor for unusual HTTP requests or traffic patterns targeting UTT nv518G web server ports. Network-based IDS/IPS signatures can detect attempts to send oversized payloads or malformed HTTP requests to the gohead component, though signature development will depend on vendor or security researcher disclosures. At the host level, check device logs for web server crashes, restarts, or error messages corresponding to the vulnerable component. Enable verbose logging on affected devices if supported.

Why prioritize this

This vulnerability merits rapid attention due to its high CVSS score (7.5), remote exploitability without authentication, and low attack complexity. Although the impact is limited to denial of service rather than data breach or remote code execution, widespread DoS attacks against critical infrastructure or managed services could cascade into significant business disruption. Prioritization should account for the role of affected UTT devices in your network architecture and the availability requirements of dependent systems.

Risk score, explained

The CVSS 3.1 score of 7.5 (HIGH) reflects a remotely exploitable network vulnerability with no authentication or user interaction barriers, resulting in high availability impact. The score does not account for data confidentiality or integrity loss, as the vulnerability does not enable unauthorized access or modification. Real-world risk depends on network exposure, device role, and the availability of a weaponized exploit; organizations with air-gapped or access-restricted devices face lower practical risk than those exposing UTT devices to untrusted networks.

Frequently asked questions