# CVE-2026-5267: Unauthenticated Event Stream Exposure of Session Tokens in Navigator NCS

> Unauthenticated attackers can access event streams to obtain sensitive session tokens in Ciena Navigator NCS.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Sep 2026
- **Updated:** 25 Sep 2026
- **Also known as:** GHSA-6mqq-ppj3-rm94

## What is CVE-2026-5267?

CVE-2026-5267 is a high-severity vulnerability in Ciena Navigator NCS, published on 25 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Ciena Navigator Network
Control Suite (NCS) contains an information exposure vulnerability in an
event-streaming API that does not properly enforce authentication. An
unauthenticated attacker with network access to the affected service could
access the event stream and potentially obtain sensitive information.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-5267?


## How do I fix CVE-2026-5267?

No fix has been published for CVE-2026-5267 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5267 being exploited?

There is no known exploitation of CVE-2026-5267 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5267 and fix it if it is affected.

What it is: CVE-2026-5267 is a high-severity vulnerability in Ciena Navigator NCS, published on 25 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5267 in the wild and no public exploit code.

Affected product: Ciena Navigator NCS. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-5267/ (Markdown: https://insights.sbomify.com/CVE-2026-5267/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5267
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5267
- OSV: https://osv.dev/vulnerability/CVE-2026-5267

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5267/
Summaries are generated and may contain mistakes; the official description above is the record.