CVE-2026-5269: Ciena Mcp

Critical severity, CVSS 9.8. EPSS: 0.5% chance of exploitation in the next 30 days.

In Ciena's Navigator Network Control Suite (NCS) and Manage Control Plan (MCP), there are hidden system accounts used for internal software operations. Some of these accounts have default passwords that may be predictable. While these accounts have very limited permissions on their own, an attacker could combine an attack using one of these accounts with other potential weaknesses to launch a more significant attack, possibly leading to escalation of privilege on the system.

Affected products

• Ciena Mcp: up to and including 8.0
• Ciena Navigator Ncs: version 8.1 only
• Ciena Planner Plus Onprem: up to and including 4.1

Published 2026-07-14. Last modified 2026-07-15.