# CVE-2021-27794: Auth bypass in Brocade Fabric OS

> Attackers can bypass authentication via empty or invalid passwords on telnet, ssh, and REST interfaces, gaining unauthorized access to Brocade Fabric OS devices.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Aug 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-pm9p-wm39-4jc9

## What is CVE-2021-27794?

CVE-2021-27794 is a high-severity authentication bypass vulnerability in Broadcom Fabric Operating System, published on 12 Aug 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the authentication mechanism of Brocade Fabric OS versions before Brocade Fabric OS v.9.0.1a, v8.2.3a and v7.4.2h could allow a user to Login with empty password, and invalid password through telnet, ssh and REST.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2021-27794?

It affects 1 product.


Products: Broadcom Fabric Operating System.

## How do I fix CVE-2021-27794?

No fix has been published for CVE-2021-27794 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27794 being exploited?

There is no known exploitation of CVE-2021-27794 in the wild and no public exploit code.

## Other vulnerabilities in Broadcom Fabric Operating System

- [CVE-2025-1976](https://insights.sbomify.com/CVE-2025-1976/): Broadcom Brocade Fabric OS Code Injection (high 8.6, exploited in the wild)
- [CVE-2021-22555](https://insights.sbomify.com/CVE-2021-22555/): Linux Kernel Heap Out-of-Bounds Write (high 8.3, exploited in the wild)
- [CVE-2022-33186](https://insights.sbomify.com/CVE-2022-33186/): Command injection in Brocade Fabric OS (critical 9.8)
- [CVE-2021-27797](https://insights.sbomify.com/CVE-2021-27797/): Hardcoded credentials in Brocade Fabric OS (critical 9.8)
- [CVE-2020-15371](https://insights.sbomify.com/CVE-2020-15371/): Code injection in Brocade Fabric OS (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27794 and fix it if it is affected.

What it is: CVE-2021-27794 is a high-severity authentication bypass vulnerability in Broadcom Fabric Operating System, published on 12 Aug 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-27794 in the wild and no public exploit code.

Affected product: Broadcom Fabric Operating System. 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-2021-27794/ (Markdown: https://insights.sbomify.com/CVE-2021-27794/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27794
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27794
- OSV: https://osv.dev/vulnerability/CVE-2021-27794

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27794/
Summaries are generated and may contain mistakes; the official description above is the record.