# CVE-2023-39950: Insufficient input validation in efibootguard

> Insufficient input validation in efibootguard allows attackers to inject code or cause crashes via manipulated bootloader environment files.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Aug 2023
- **Updated:** 1 Oct 2024
- **Also known as:** DEBIAN-CVE-2023-39950, GHSA-j6pp-7g99-24m7, UBUNTU-CVE-2023-39950

## What is CVE-2023-39950?

CVE-2023-39950 is a medium-severity code injection vulnerability in siemens efibootguard, published on 14 Aug 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

efibootguard is a simple UEFI boot loader with support for safely switching between current and updated partition sets. Insufficient or missing validation and sanitization of input from untrustworthy bootloader environment files can cause crashes and probably also code injections into `bg_setenv`) or programs using `libebgenv`. This is triggered when the affected components try to modify a manipulated environment, in particular its user variables. Furthermore, `bg_printenv` may crash over invalid read accesses or report invalid results. Not affected by this issue is EFI Boot Guard's bootloader EFI binary. EFI Boot Guard release v0.15 contains required patches to sanitize and validate the bootloader environment prior to processing it in userspace. Its library and tools should be updated, so should programs statically linked against it. An update of the bootloader EFI executable is not required. The only way to prevent the issue with an unpatched EFI Boot Guard version is to avoid accesses to user variables, specifically modifications to them.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2023-39950?

It affects 1 product.


Products: Siemens Efibootguard.

## How do I fix CVE-2023-39950?

Upgrade to a fixed version.

## Is CVE-2023-39950 being exploited?

There is no known exploitation of CVE-2023-39950 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-39950 and fix it if it is affected.

What it is: CVE-2023-39950 is a medium-severity code injection vulnerability in siemens efibootguard, published on 14 Aug 2023. 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-2023-39950 in the wild and no public exploit code.

Affected product: siemens efibootguard. 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-2023-39950/ (Markdown: https://insights.sbomify.com/CVE-2023-39950/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-39950
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-39950
- OSV: https://osv.dev/vulnerability/CVE-2023-39950

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-39950/
Summaries are generated and may contain mistakes; the official description above is the record.