# CVE-2021-43399: Memory corruption in n/a

> Improper length validation in the YubiHSM2 library allows attackers to trigger memory corruption via crafted SSH signing requests or data operations.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:** No
- **Published:** 8 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-vrp3-rwcp-4q77

## What is CVE-2021-43399?

CVE-2021-43399 is a high-severity memory corruption vulnerability in n/a, published on 8 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Yubico YubiHSM YubiHSM2 library 2021.08, included in the yubihsm-shell project, does not properly validate the length of some operations including SSH signing requests, and some data operations received from a YubiHSM 2 device.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-43399?

It affects 1 product.


Products: Yubico Yubihsm 2 Software Development Kit.

## How do I fix CVE-2021-43399?

No fix has been published for CVE-2021-43399 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-43399 being exploited?

There is no known exploitation of CVE-2021-43399 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43399 and fix it if it is affected.

What it is: CVE-2021-43399 is a high-severity memory corruption vulnerability in n/a, published on 8 Dec 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-2021-43399 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-2021-43399/ (Markdown: https://insights.sbomify.com/CVE-2021-43399/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43399
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43399
- OSV: https://osv.dev/vulnerability/CVE-2021-43399

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43399/
Summaries are generated and may contain mistakes; the official description above is the record.