# CVE-2020-11933: local snapd exploit through cloud-init

> A physical attacker can bypass full disk encryption on Ubuntu Core devices by exploiting unrestricted cloud-init execution during boot via external media.

- **Severity:** High 7.3 (`CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N`)
- **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:** 29 Jul 2020
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-v343-8p34-76p3

## What is CVE-2020-11933?

CVE-2020-11933 is a high-severity vulnerability in Canonical Ubuntu Linux, published on 29 Jul 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

cloud-init as managed by snapd on Ubuntu Core 16 and Ubuntu Core 18 devices was run without restrictions on every boot, which a physical attacker could exploit by crafting cloud-init user-data/meta-data via external media to perform arbitrary changes on the device to bypass intended security mechanisms such as full disk encryption. This issue did not affect traditional Ubuntu systems. Fixed in snapd version 2.45.2, revision 8539 and core version 2.45.2, revision 9659.

Weakness: CWE-264

## Which versions are affected by CVE-2020-11933?

It affects 2 products.


Products: Canonical Snapd, Canonical Ubuntu Linux.

## How do I fix CVE-2020-11933?

No fix has been published for CVE-2020-11933 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-11933 being exploited?

There is no known exploitation of CVE-2020-11933 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2023-1523](https://insights.sbomify.com/CVE-2023-1523/): Command injection in snapd (critical 10.0)
- [CVE-2020-27352](https://insights.sbomify.com/CVE-2020-27352/): Privilege escalation in snapd (critical 9.3)
- [CVE-2019-7304](https://insights.sbomify.com/CVE-2019-7304/): Local privilege escalation via snapd socket (high 8.8)
- [CVE-2021-4120](https://insights.sbomify.com/CVE-2021-4120/): snapd could be made to bypass intended access restrictions through snap content interfaces and layout paths (high 8.2)
- [CVE-2024-5138](https://insights.sbomify.com/CVE-2024-5138/): CVE-2024-5138: snapd snapctl auth bypass (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-11933 and fix it if it is affected.

What it is: CVE-2020-11933 is a high-severity vulnerability in Canonical Ubuntu Linux, published on 29 Jul 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-2020-11933 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. 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-2020-11933/ (Markdown: https://insights.sbomify.com/CVE-2020-11933/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-11933
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-11933
- OSV: https://osv.dev/vulnerability/CVE-2020-11933

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-11933/
Summaries are generated and may contain mistakes; the official description above is the record.