# CVE-2026-5269 — CIENA Navigator NCS

> As of 2026-07-15, CVE-2026-5269 is a CRITICAL-severity vulnerability in CIENA Navigator NCS, CVSS v3.1 9.8, EPSS 0.1% (4.1th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-5269 as of 2026-07-15; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-07-15

## What is CVE-2026-5269?

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.

The record classifies CVE-2026-5269 under weakness class [CWE-1393](https://cwe.mitre.org/data/definitions/1393.html). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 3 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 83 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 9.8 — CRITICAL (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **EPSS (FIRST):** 0.1% probability of exploitation in the next 30 days, higher than 4.1% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.1/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-14, last modified 2026-07-15

## Is CVE-2026-5269 being exploited?

It currently carries a trending score of 31 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **CIENA**: Navigator NCS, MCP, Planner Plus OnPrem

## How to fix CVE-2026-5269

No vendor patch reference has been recorded for CVE-2026-5269 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-5269

No threat campaign in the Threadlinqs corpus currently references CVE-2026-5269, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-07-15. This product uses the NVD API but is not endorsed or certified by the NVD.

**Other references**

- [ciena.com](https://www.ciena.com/product-security)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-5269
Full detection coverage and IOCs for threats exploiting CVE-2026-5269 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp