# CVE-2021-3849: Auth bypass in Fan Power Controller2 (FPC2)

> Unauthenticated attackers can bypass authentication in Lenovo FPC2 and SMM web interfaces to execute arbitrary commands on the devices.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 Apr 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-vxqg-r9mf-h85v

## What is CVE-2021-3849?

CVE-2021-3849 is a critical authentication bypass vulnerability in Lenovo Fan Power Controller2 (FPC2), published on 22 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An authentication bypass vulnerability was discovered in the web interface of the Lenovo Fan Power Controller2 (FPC2) and Lenovo System Management Module (SMM) firmware that could allow an unauthenticated attacker to execute commands on the SMM and FPC2. SMM2 is not affected.

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

## Which versions are affected by CVE-2021-3849?

It affects 5 products.


Products: Ibm Nextscale Fan Power Controller Firmware, Lenovo Nextscale N1200 Enclosure Firmware, Lenovo Thinkagile Hx Enclosure Certified Node Firmware, Lenovo Thinkagile Vx Enclosure Firmware, Lenovo Thinksystem D2 Enclosure Firmware.

## How do I fix CVE-2021-3849?

No fix has been published for CVE-2021-3849 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-3849 being exploited?

There is no known exploitation of CVE-2021-3849 in the wild and no public exploit code.

## Other vulnerabilities in Lenovo Fan Power Controller2 (FPC2)

- [CVE-2021-3897](https://insights.sbomify.com/CVE-2021-3897/): Auth bypass in Fan Power Controller2 (FPC2) (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3849 and fix it if it is affected.

What it is: CVE-2021-3849 is a critical authentication bypass vulnerability in Lenovo Fan Power Controller2 (FPC2), published on 22 Apr 2022. 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-2021-3849 in the wild and no public exploit code.

Affected product: Lenovo Fan Power Controller2 (FPC2). 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-2021-3849/ (Markdown: https://insights.sbomify.com/CVE-2021-3849/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3849
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3849
- OSV: https://osv.dev/vulnerability/CVE-2021-3849

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3849/
Summaries are generated and may contain mistakes; the official description above is the record.