Review reviewCritical

CVE-2026-5270

CIENA Navigator NCS, MCP, Planner Plus OnPrem

An authentication bypass vulnerability exists in certain releases of Ciena Navigator Network Control Suite (NCS), Manage Control Plan (MCP), and Blue Planet products. The issue is caused by improper handling of HTTP request paths and headers, which allows an unauthenticated attacker to manipulate requests in a manner that bypasses authentication and associated audit logging controls.

CVSS: 9.8
EPSS: 0.45%
CISA KEV: Not listed
Published: 2026.07.15

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.45%

Technical severityCVSS 9.8

Vulnerability overview

Affected product and versions

Product: CIENA Navigator NCS, MCP, Planner Plus OnPrem
Affected versions: >= 8.1, >= <= 8.0, >= <= 4.1, >= <=24.04.001, >= <=23.12.401, >= <=23.08.302, >= <=23.04.701, >= <=24.04.2, >= <=23.12.3, >= <=23.08.4, >= <=23.04.2, >= <=24.04.1.2-R, >= <=23.12.1.6-R, >= <=23.08.1.6-R, >= <=23.04.P01-9-R, >= <=24.04 MR1, >= <=23.12 MR3, >= <=23.04. MR4
Fixed versions: No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that CIENA Navigator NCS, MCP, Planner Plus OnPrem and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE: CWE-287