CVE-2018-0378: Cisco NX-OS Software for Nexus 5500, 5600, and 6000 Series Switches Precision Time Protocol Denial of Service Vulnerability

Security readout for executives and security teams

This flaw can let an unauthenticated remote attacker overwhelm affected Cisco Nexus switches with Precision Time Protocol traffic, causing a denial of service that can disrupt traffic passing through the switch. The business impact is availability: network segments relying on these switches could experience outages or degraded service if exposed to hostile PTP traffic. Exposure is most relevant where Cisco Nexus 5500, 5600, or 6000 Series switches run affected NX-OS with PTP reachable from untrusted or broad internal networks. The source bundle only provides one explicit affected version entry, so confirm exact platform and release coverage against Cisco guidance. Handle as a near-term infrastructure availability issue. It does not expose data directly, but a successful attack could disrupt traffic through core or data-center switching. Prioritize internet-adjacent or broadly reachable internal switches first, then complete version validation across the Nexus estate. Mitigation focus: Review Cisco advisory cisco-sa-20181017-nexus-ptp-dos for fixed releases and workarounds.; Prioritize upgrade or vendor-recommended remediation for affected Nexus switches.; Restrict PTP traffic to trusted time-synchronization sources where operationally possible..

Prepared

May 23, 2026, 09:01 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.