Overview

CVE-2026-76659 is a vulnerability in the finger daemon of HPE NonStop TCP/IP UTILITIES. This vulnerability could allow an unauthenticated remote attacker to cause a denial of service. The affected product is HPE NonStop TCP/IP UTILITIES, specifically version T8602L01^BAA and earlier.

Understanding the Vulnerability / Threat

Root Cause Analysis

The root cause of this vulnerability is a design issue in the finger daemon of HPE NonStop TCP/IP UTILITIES. This issue falls under the CWE-306 category, which relates to missing authentication for critical functionality. The vulnerability allows an unauthenticated remote attacker to cause a denial of service, indicating that the issue lies in the lack of proper authentication and potentially insufficient input validation or error handling.

Attack Surface & Vector

The attack surface for this vulnerability is the network. An attacker can reach this vulnerability remotely without needing any authentication or privileges. The vector for exploitation involves sending a malicious request to the finger daemon running on the affected system.

Exploitation Mechanics — Scenario Walkthrough

Scenario: Compromising Availability of a Corporate HPE NonStop TCP/IP UTILITIES Instance 1. Initial Position: The attacker is an unauthenticated remote user with network access to the affected HPE NonStop TCP/IP UTILITIES system. 2. Triggering the Flaw: The attacker crafts a malicious request to the finger daemon running on the affected system. This request is designed to exploit the vulnerability, potentially by providing specially crafted input that leads to a denial of service condition. 3. What Breaks: The security boundary that fails is the lack of authentication and possibly insufficient input validation or error handling in the finger daemon. This allows the attacker to cause the service to become unavailable. 4. Attacker's Prize: The attacker successfully causes a denial of service condition, making the HPE NonStop TCP/IP UTILITIES instance unavailable. This could lead to operational disruptions and potentially impact business continuity.

Real-World Impact

The real-world impact of this vulnerability is significant. An attacker could exploit this vulnerability to disrupt the availability of critical systems, leading to operational downtime and potential financial losses. Although there is no confirmation of active exploitation, the high CVSS score and the potential for denial of service attacks make it essential for affected organizations to apply mitigations promptly.

Detection & Defense

Immediate Mitigations

- Upgrade HPE NonStop TCP/IP UTILITIES to a version later than T8602L01^BAA. - Apply the patch or update provided by HPE as referenced in https://support.hpe.com/hpesc/public/docDisplay?docId=hpesbns05148en_us&docLocale=en_US.

Detection Strategies

- Monitor network traffic for unusual patterns of requests to the finger daemon. - Implement SIEM rules to detect and alert on potential exploitation attempts. - Regularly review system logs for signs of denial of service attacks.

Long-Term Hardening

- Implement robust input validation and error handling for network services. - Limit access to critical network services like the finger daemon. - Regularly update and patch systems to prevent exploitation of known vulnerabilities.

Key Takeaways

- CVE-2026-76659 is a high-severity vulnerability in HPE NonStop TCP/IP UTILITIES that can lead to denial of service. - The vulnerability is caused by a lack of authentication in the finger daemon. - Immediate mitigation involves upgrading to a later version or applying a patch. - Detection strategies include monitoring network traffic and system logs. - Long-term hardening involves robust input validation, limiting access, and regular updates.

Sources

- National Vulnerability Database (NVD) - https://nvd.nist.gov/vuln/detail/CVE-2026-76659 - HPE Support Document - https://support.hpe.com/hpesc/public/docDisplay?docId=hpesbns05148en_us&docLocale=en_US