# CVE-2021-3786: Information disclosure in Notebook and ThinkPad BIOS

> An attacker can exploit an SMI callback flaw in Lenovo BIOS to leak sensitive data from SMRAM, requiring firmware updates to mitigate.

- **Severity:** Medium 4.4 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Nov 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-mxm2-jrgh-833g

## What is CVE-2021-3786?

CVE-2021-3786 is a medium-severity vulnerability in Lenovo Notebook and ThinkPad BIOS, published on 12 Nov 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A potential vulnerability in the SMI callback function used in CSME configuration of some Lenovo Notebook and ThinkPad systems could be used to leak out data out of the SMRAM range.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-3786?

It affects 133 products.


Products: Lenovo Ideapad S940-14iwl Firmware, Lenovo Ideapad Yoga S940-14iwl Firmware, Lenovo Thinkpad 10 Firmware, Lenovo Thinkpad 11e 3rd Gen Firmware, Lenovo Thinkpad 11e 4th Gen Firmware, Lenovo Thinkpad 11e Yoga Gen 6 Firmware, Lenovo Thinkpad 13 Gen 2 Firmware, Lenovo Thinkpad 25 Firmware, Lenovo Thinkpad E14 Firmware, Lenovo Thinkpad E14 Gen 2 Firmware, Lenovo Thinkpad E14 Gen 3 Firmware, Lenovo Thinkpad E15 Firmware, Lenovo Thinkpad E15 Gen 2 Firmware, Lenovo Thinkpad E15 Gen 3 Firmware, Lenovo Thinkpad E470 Firmware, Lenovo Thinkpad E480 Firmware, Lenovo Thinkpad E490 Firmware, Lenovo Thinkpad E570 Firmware, Lenovo Thinkpad E580 Firmware, Lenovo Thinkpad E590 Firmware and 113 more.

## How do I fix CVE-2021-3786?

No fix has been published for CVE-2021-3786 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-3786 being exploited?

There is no known exploitation of CVE-2021-3786 in the wild and no public exploit code.

## Other vulnerabilities in Lenovo Notebook and ThinkPad BIOS

- [CVE-2021-3599](https://insights.sbomify.com/CVE-2021-3599/): Privilege escalation in ThinkPad BIOS (medium 6.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3786 and fix it if it is affected.

What it is: CVE-2021-3786 is a medium-severity vulnerability in Lenovo Notebook and ThinkPad BIOS, published on 12 Nov 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-2021-3786 in the wild and no public exploit code.

Affected product: Lenovo Notebook and ThinkPad BIOS. 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-2021-3786/ (Markdown: https://insights.sbomify.com/CVE-2021-3786/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3786
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3786
- OSV: https://osv.dev/vulnerability/CVE-2021-3786

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-3786/
Summaries are generated and may contain mistakes; the official description above is the record.