# CVE-2021-27047: HEVC Video Extensions Remote Code Execution Vulnerability

> An attacker can execute arbitrary code via the HEVC Video Extensions component in Microsoft Windows.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 11 Mar 2021
- **Updated:** 19 Aug 2026
- **Also known as:** GHSA-53m4-2cjq-376q

## What is CVE-2021-27047?

CVE-2021-27047 is a high-severity code injection vulnerability in Microsoft HEVC Video Extensions, published on 11 Mar 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

HEVC Video Extensions Remote Code Execution Vulnerability

## Which versions are affected by CVE-2021-27047?

It affects 1 product.


Products: Microsoft High Efficiency Video Coding.

## How do I fix CVE-2021-27047?

No fix has been published for CVE-2021-27047 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27047 being exploited?

There is no known exploitation of CVE-2021-27047 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft HEVC Video Extensions

- [CVE-2021-24089](https://insights.sbomify.com/CVE-2021-24089/): HEVC Video Extensions Remote Code Execution Vulnerability (high 7.8)
- [CVE-2021-24110](https://insights.sbomify.com/CVE-2021-24110/): HEVC Video Extensions Remote Code Execution Vulnerability (high 7.8)
- [CVE-2021-26902](https://insights.sbomify.com/CVE-2021-26902/): HEVC Video Extensions Remote Code Execution Vulnerability (high 7.8)
- [CVE-2021-27048](https://insights.sbomify.com/CVE-2021-27048/): HEVC Video Extensions Remote Code Execution Vulnerability (high 7.8)
- [CVE-2021-27049](https://insights.sbomify.com/CVE-2021-27049/): HEVC Video Extensions Remote Code Execution Vulnerability (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27047 and fix it if it is affected.

What it is: CVE-2021-27047 is a high-severity code injection vulnerability in Microsoft HEVC Video Extensions, published on 11 Mar 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-27047 in the wild and no public exploit code.

Affected product: Microsoft HEVC Video Extensions. 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-2021-27047/ (Markdown: https://insights.sbomify.com/CVE-2021-27047/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27047
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27047
- OSV: https://osv.dev/vulnerability/CVE-2021-27047

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-27047/
Summaries are generated and may contain mistakes; the official description above is the record.