# CVE-2020-10021: Out-of-bounds write in USB Mass Storage with unaligned sizes

> An out-of-bounds write in the USB Mass Storage handler allows attackers to execute arbitrary code or cause a denial of service.

- **Severity:** High 8.1 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 11 May 2020
- **Updated:** 17 Sep 2024
- **Also known as:** CVE-2020-10026, GHSA-7r7c-7m5r-6gpx

## What is CVE-2020-10021?

CVE-2020-10021 is a high-severity memory corruption vulnerability in Zephyrproject Zephyr, published on 11 May 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Out-of-bounds Write in the USB Mass Storage memoryWrite handler with unaligned Sizes See NCC-ZEP-024, NCC-ZEP-025, NCC-ZEP-026 This issue affects: zephyrproject-rtos zephyr version 1.14.1 and later versions. version 2.1.0 and later versions.

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

## Which versions are affected by CVE-2020-10021?

It affects 1 product.


Products: Zephyrproject Zephyr.

## How do I fix CVE-2020-10021?

No fix has been published for CVE-2020-10021 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-10021 being exploited?

There is no known exploitation of CVE-2020-10021 in the wild and no public exploit code.

## Other vulnerabilities in Zephyrproject Zephyr

- [CVE-2026-5067](https://insights.sbomify.com/CVE-2026-5067/): Out-of-bounds read/write in HTTP WebSocket upgrade via non-null-terminated Sec-WebSocket-Key (critical 9.8)
- [CVE-2022-3806](https://insights.sbomify.com/CVE-2022-3806/): Bluetooth HCI Error Handling Double Free (critical 9.8)
- [CVE-2017-14199](https://insights.sbomify.com/CVE-2017-14199/): Memory corruption in getaddrinfo (critical 9.8)
- [CVE-2018-1000800](https://insights.sbomify.com/CVE-2018-1000800/): Null dereference in n/a (critical 9.8)
- [CVE-2021-3329](https://insights.sbomify.com/CVE-2021-3329/): DOS: Incorrect handling of the initial HCI ACL_MTU handshake packet leads to crash of bluetooth host layer (critical 9.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-10021 and fix it if it is affected.

What it is: CVE-2020-10021 is a high-severity memory corruption vulnerability in Zephyrproject Zephyr, published on 11 May 2020. 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-2020-10021 in the wild and no public exploit code.

Affected product: Zephyrproject Zephyr. 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-2020-10021/ (Markdown: https://insights.sbomify.com/CVE-2020-10021/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-10021
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-10021
- OSV: https://osv.dev/vulnerability/CVE-2020-10021

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-10021/
Summaries are generated and may contain mistakes; the official description above is the record.