# CVE-2026-86421: ImageMagick before 7.1.2-30 Memory Leak via MSL decoder

> A memory leak in the MSL decoder allows attackers to exhaust system memory and cause denial of service via crafted images.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Sep 2026
- **Updated:** 29 Oct 2026
- **Also known as:** CLSA-2026-1789486747, CLSA-2026-1789565568, CLSA-2026-1791925507, DEBIAN-CVE-2026-86421, ECHO-435d-018f-25c9, GHSA-4jv7-q6xw-6f4x, GHSA-vv85-m77w-hhgx, MINI-pm76-2mf4-3xq2, UBUNTU-CVE-2026-86421

## What is CVE-2026-86421?

CVE-2026-86421 is a medium-severity denial of service vulnerability in Imagemagick Imagemagick, published on 7 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ImageMagick before 7.1.2-30 and 6.9.13-55 contains a memory leak in the MSL image decoder. A crafted MSL image triggers memory allocation without proper deallocation, allowing an attacker to exhaust memory and cause a denial of service.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-86421?

It affects 1 product.


Products: Imagemagick Imagemagick.

## How do I fix CVE-2026-86421?

Upgrade to a fixed version.

## Is CVE-2026-86421 being exploited?

There is no known exploitation of CVE-2026-86421 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-2026-86421 and fix it if it is affected.

What it is: CVE-2026-86421 is a medium-severity denial of service vulnerability in Imagemagick Imagemagick, published on 7 Sep 2026. 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-2026-86421 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-2026-86421/ (Markdown: https://insights.sbomify.com/CVE-2026-86421/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86421
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86421
- OSV: https://osv.dev/vulnerability/CVE-2026-86421

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-86421/
Summaries are generated and may contain mistakes; the official description above is the record.