# CVE-2021-36691: Denial of service in n/a

> An attacker can cause a denial of service by providing a malicious GIF file to the JPEG XL encoder, triggering an assertion failure.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 30 Aug 2021
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-36691, GHSA-fg2p-g438-rjr4, UBUNTU-CVE-2021-36691

## What is CVE-2021-36691?

CVE-2021-36691 is a high-severity denial of service vulnerability in n/a, published on 30 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libjxl v0.5.0 is affected by a Assertion failed issue in lib/jxl/image.cc jxl::PlaneBase::PlaneBase(). When encoding a malicous GIF file using cjxl, an attacker can trigger a denial of service.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2021-36691?

It affects 1 product.


Products: Libjxl Project Libjxl.

## How do I fix CVE-2021-36691?

No fix has been published for CVE-2021-36691 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-36691 being exploited?

There is no known exploitation of CVE-2021-36691 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-27804](https://insights.sbomify.com/CVE-2021-27804/): Memory corruption in n/a (critical 9.8)
- [CVE-2026-1837](https://insights.sbomify.com/CVE-2026-1837/): libjxl: Out-of-bounds write in grayscale color transformation when using LCMS2 (high 8.7)
- [CVE-2023-35790](https://insights.sbomify.com/CVE-2023-35790/): Integer overflow in n/a (high 7.5)
- [CVE-2024-11403](https://insights.sbomify.com/CVE-2024-11403/): Out of Bounds Memory Read/Write in libjxl (medium 6.9)
- [CVE-2024-11498](https://insights.sbomify.com/CVE-2024-11498/): Resource exhaustion via Stack overflow in libjxl (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-36691 and fix it if it is affected.

What it is: CVE-2021-36691 is a high-severity denial of service vulnerability in n/a, published on 30 Aug 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-2021-36691 in the wild and no public exploit code.

Affected product: n/a. 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-2021-36691/ (Markdown: https://insights.sbomify.com/CVE-2021-36691/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-36691
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-36691
- OSV: https://osv.dev/vulnerability/CVE-2021-36691

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-36691/
Summaries are generated and may contain mistakes; the official description above is the record.