# CVE-2021-40418: Use after free in Blackmagic Design

> An attacker can achieve code execution by submitting a malicious file to the DPDecoder service, exploiting an uninitialized pointer dereference in the R3D SDK.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 22 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-c57m-77h8-88cm

## What is CVE-2021-40418?

CVE-2021-40418 is a critical use after free vulnerability in Blackmagic Design, published on 22 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

When parsing a file that is submitted to the DPDecoder service as a job, the R3D SDK will mistakenly skip over the assignment of a property containing an object referring to a UUID that was parsed from a frame within the video container. Upon destruction of the object that owns it, the uninitialized member will be dereferenced and then destroyed using the object’s virtual destructor. Due to the object property being uninitialized, this can result in dereferencing an arbitrary pointer for the object’s virtual method table, which can result in code execution under the context of the application.

Weakness: CWE-908 (Use of Uninitialized Resource), CWE-457 (Use of Uninitialized Variable)

## Which versions are affected by CVE-2021-40418?

It affects 1 product.


Products: Blackmagicdesign Davinci Resolve.

## How do I fix CVE-2021-40418?

No fix has been published for CVE-2021-40418 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-40418 being exploited?

There is no known exploitation of CVE-2021-40418 in the wild and no public exploit code.

## Other vulnerabilities in Blackmagic Design

- [CVE-2021-40417](https://insights.sbomify.com/CVE-2021-40417/): Integer overflow in Blackmagic Design (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-40418 and fix it if it is affected.

What it is: CVE-2021-40418 is a critical use after free vulnerability in Blackmagic Design, published on 22 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-2021-40418 in the wild and no public exploit code.

Affected product: Blackmagic Design. 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-2021-40418/ (Markdown: https://insights.sbomify.com/CVE-2021-40418/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40418
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40418
- OSV: https://osv.dev/vulnerability/CVE-2021-40418

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40418/
Summaries are generated and may contain mistakes; the official description above is the record.