# CVE-2026-5268: SFTP Server Authentication Weakness

> Remote attackers can bypass SFTP authentication to read or modify system files on Ciena network devices.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 6 Jul 2026
- **Updated:** 8 Jul 2026
- **Also known as:** GHSA-m6c7-7xhp-6vhc

## What is CVE-2026-5268?

CVE-2026-5268 is a critical authentication bypass vulnerability in CIENA 6500 S-Series, published on 6 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An authentication bypass vulnerability exists in
the default SFTP server component utilized across the Ciena products listed. This vulnerability allows a remote, unauthenticated attacker to bypass
security controls and gain unauthorized access to the underlying filesystem.
Successful exploitation could allow an attacker to read or modify system files.

Weakness: CWE-288 (Authentication Bypass Using an Alternate Path or Channel)

## Which versions are affected by CVE-2026-5268?


## How do I fix CVE-2026-5268?

No fix has been published for CVE-2026-5268 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5268 being exploited?

There is no known exploitation of CVE-2026-5268 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5268 and fix it if it is affected.

What it is: CVE-2026-5268 is a critical authentication bypass vulnerability in CIENA 6500 S-Series, published on 6 Jul 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-2026-5268 in the wild and no public exploit code.

Affected product: CIENA 6500 S-Series. 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-2026-5268/ (Markdown: https://insights.sbomify.com/CVE-2026-5268/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5268
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5268
- OSV: https://osv.dev/vulnerability/CVE-2026-5268

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5268/
Summaries are generated and may contain mistakes; the official description above is the record.