# CVE-2021-27217: Denial of service in n/a

> An attacker can cause a client-side denial of service in the YubiHSM 2 SDK by triggering an out-of-bounds read via malformed messages.

- **Severity:** Medium 4.4 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Mar 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-2xj6-87qq-8g95

## What is CVE-2021-27217?

CVE-2021-27217 is a medium-severity denial of service vulnerability in n/a, published on 4 Mar 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

An issue was discovered in the _send_secure_msg() function of Yubico yubihsm-shell through 2.0.3. The function does not correctly validate the embedded length field of an authenticated message received from the device. Out-of-bounds reads performed by aes_remove_padding() can crash the running process, depending on the memory layout. This could be used by an attacker to cause a client-side denial of service. The yubihsm-shell project is included in the YubiHSM 2 SDK product.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2021-27217?

It affects 1 product.


Products: Yubico Yubihsm-Shell.

## How do I fix CVE-2021-27217?

No fix has been published for CVE-2021-27217 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27217 being exploited?

There is no known exploitation of CVE-2021-27217 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-32489](https://insights.sbomify.com/CVE-2021-32489/): Integer overflow in n/a (medium 4.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27217 and fix it if it is affected.

What it is: CVE-2021-27217 is a medium-severity denial of service vulnerability in n/a, published on 4 Mar 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-27217 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-2021-27217/ (Markdown: https://insights.sbomify.com/CVE-2021-27217/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27217
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27217
- OSV: https://osv.dev/vulnerability/CVE-2021-27217

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27217/
Summaries are generated and may contain mistakes; the official description above is the record.