# CVE-2021-28495: Auth bypass in Metamako Operating System

> Attackers can bypass user authentication on Arista Metamako devices when JSON-RPC API access is enabled, potentially gaining unauthorized access.

- **Severity:** High 7.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Sep 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-cpvp-q5mv-cx2q

## What is CVE-2021-28495?

CVE-2021-28495 is a high-severity authentication bypass vulnerability in Arista Metamako Operating System, published on 9 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In Arista's MOS (Metamako Operating System) software which is supported on the 7130 product line, under certain conditions, user authentication can be bypassed when API access is enabled via the JSON-RPC APIs. This issue affects: Arista Metamako Operating System All releases in the MOS-0.1x train MOS-0.13 and post releases in the MOS-0.1x train MOS-0.26.6 and below releases in the MOS-0.2x train MOS-0.31.1 and below releases in the MOS-0.3x train

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2021-28495?

It affects 1 product.


Products: Arista Metamako Operating System.

## How do I fix CVE-2021-28495?

No fix has been published for CVE-2021-28495 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-28495 being exploited?

There is no known exploitation of CVE-2021-28495 in the wild and no public exploit code.

## Other vulnerabilities in Arista Metamako Operating System

- [CVE-2021-28494](https://insights.sbomify.com/CVE-2021-28494/): Auth bypass in Metamako Operating System (critical 9.6)
- [CVE-2021-28498](https://insights.sbomify.com/CVE-2021-28498/): Hardcoded credentials in Metamako Operating System (high 8.7)
- [CVE-2021-28493](https://insights.sbomify.com/CVE-2021-28493/): Auth bypass in Metamako Operating System (high 8.4)
- [CVE-2021-28499](https://insights.sbomify.com/CVE-2021-28499/): Information disclosure in Metamako Operating System (medium 6.3)
- [CVE-2021-28497](https://insights.sbomify.com/CVE-2021-28497/): Auth bypass in Metamako Operating System (medium 4.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28495 and fix it if it is affected.

What it is: CVE-2021-28495 is a high-severity authentication bypass vulnerability in Arista Metamako Operating System, published on 9 Sep 2021. 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-2021-28495 in the wild and no public exploit code.

Affected product: Arista Metamako 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-2021-28495/ (Markdown: https://insights.sbomify.com/CVE-2021-28495/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28495
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28495
- OSV: https://osv.dev/vulnerability/CVE-2021-28495

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28495/
Summaries are generated and may contain mistakes; the official description above is the record.