# CVE-2021-40400: Information disclosure in Gerbv

> An out-of-bounds read in Gerbv allows attackers to disclose information via a specially crafted Gerber file.

- **Severity:** Critical 9.3 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Apr 2022
- **Updated:** 15 Apr 2025
- **Also known as:** DEBIAN-CVE-2021-40400, GHSA-6c2w-p226-q9q8, UBUNTU-CVE-2021-40400

## What is CVE-2021-40400?

CVE-2021-40400 is a critical vulnerability in Gerbv, published on 14 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An out-of-bounds read vulnerability exists in the RS-274X aperture macro outline primitive functionality of Gerbv 2.7.0 and dev (commit b5f1eacd) and the forked version of Gerbv (commit d7f42a9a). A specially-crafted Gerber file can lead to information disclosure. An attacker can provide a malicious file to trigger this vulnerability.

Weakness: CWE-125 (Out-of-bounds Read), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2021-40400?

It affects 1 product.


Products: Gerbv Project Gerbv.

## How do I fix CVE-2021-40400?

Apply the vendor's patch.

## Is CVE-2021-40400 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-40400 exists.

## Other vulnerabilities in Gerbv

- [CVE-2021-40402](https://insights.sbomify.com/CVE-2021-40402/): Information disclosure in Gerbv (critical 9.3)
- [CVE-2023-4508](https://insights.sbomify.com/CVE-2023-4508/): Denial of Service in Gerbv (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-40400 and fix it if it is affected.

What it is: CVE-2021-40400 is a critical vulnerability in Gerbv, published on 14 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-40400 exists.

Affected product: Gerbv. 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-2021-40400/ (Markdown: https://insights.sbomify.com/CVE-2021-40400/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40400
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40400
- OSV: https://osv.dev/vulnerability/CVE-2021-40400

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40400/
Summaries are generated and may contain mistakes; the official description above is the record.