# CVE-2021-37847: Information disclosure in n/a

> An attacker can exploit timing side-channels in digest verification to leak sensitive information from the barebox bootloader.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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:** 2 Aug 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-4xwg-632r-5463

## What is CVE-2021-37847?

CVE-2021-37847 is a high-severity vulnerability in n/a, published on 2 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

crypto/digest.c in Pengutronix barebox through 2021.07.0 leaks timing information because memcmp is used during digest verification.

## Which versions are affected by CVE-2021-37847?

It affects 1 product.


Products: Pengutronix Barebox.

## How do I fix CVE-2021-37847?

No fix has been published for CVE-2021-37847 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-37847 being exploited?

There is no known exploitation of CVE-2021-37847 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2019-15937](https://insights.sbomify.com/CVE-2019-15937/): Memory corruption in n/a (critical 9.8)
- [CVE-2019-15938](https://insights.sbomify.com/CVE-2019-15938/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-13910](https://insights.sbomify.com/CVE-2020-13910/): Information disclosure in n/a (critical 9.1)
- [CVE-2026-34963](https://insights.sbomify.com/CVE-2026-34963/): barebox EFI PE Loader Memory Safety Vulnerabilities (high 8.6)
- [CVE-2026-33243](https://insights.sbomify.com/CVE-2026-33243/): barebox: FIT Signature Verification Bypass Vulnerability (high 8.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-37847 and fix it if it is affected.

What it is: CVE-2021-37847 is a high-severity vulnerability in n/a, published on 2 Aug 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-2021-37847 in the wild and no public exploit code.

Affected product: n/a. 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-2021-37847/ (Markdown: https://insights.sbomify.com/CVE-2021-37847/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-37847
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-37847
- OSV: https://osv.dev/vulnerability/CVE-2021-37847

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-37847/
Summaries are generated and may contain mistakes; the official description above is the record.