# CVE-2021-3962: Use after free in ImageMagick

> Attackers can trigger a use-after-free in ImageMagick via crafted images, potentially leading to code execution or denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/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:** A user has to click or open something
- **Fix available:** No
- **Published:** 19 Nov 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-mp8r-x7vv-mqvq

## What is CVE-2021-3962?

CVE-2021-3962 is a high-severity use after free vulnerability in Imagemagick Imagemagick, published on 19 Nov 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

A flaw was found in ImageMagick where it did not properly sanitize certain input before using it to invoke convert processes. This flaw allows an attacker to create a specially crafted image that leads to a use-after-free vulnerability when processed by ImageMagick. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2021-3962?

It affects 1 product.


Products: Imagemagick Imagemagick.

## How do I fix CVE-2021-3962?

No fix has been published for CVE-2021-3962 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-3962 being exploited?

There is no known exploitation of CVE-2021-3962 in the wild and no public exploit code.

## Other vulnerabilities in Imagemagick Imagemagick

- [CVE-2019-19952](https://insights.sbomify.com/CVE-2019-19952/): Use after free in n/a (critical 9.8)
- [CVE-2018-16328](https://insights.sbomify.com/CVE-2018-16328/): Null dereference in n/a (critical 9.8)
- [CVE-2018-16329](https://insights.sbomify.com/CVE-2018-16329/): Null dereference in n/a (critical 9.8)
- [CVE-2017-18210](https://insights.sbomify.com/CVE-2017-18210/): Null dereference in n/a (critical 9.8)
- [CVE-2017-14138](https://insights.sbomify.com/CVE-2017-14138/): Denial of service in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3962 and fix it if it is affected.

What it is: CVE-2021-3962 is a high-severity use after free vulnerability in Imagemagick Imagemagick, published on 19 Nov 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-2021-3962 in the wild and no public exploit code.

Affected product: Imagemagick Imagemagick. 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-2021-3962/ (Markdown: https://insights.sbomify.com/CVE-2021-3962/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3962
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3962
- OSV: https://osv.dev/vulnerability/CVE-2021-3962

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3962/
Summaries are generated and may contain mistakes; the official description above is the record.