# CVE-2021-33797: Integer overflow in mujs

> An integer overflow in MuJS leads to a buffer overflow, potentially allowing attackers to execute arbitrary code or cause denial of service.

- **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:** Yes
- **Published:** 17 Apr 2023
- **Updated:** 6 Feb 2025
- **Also known as:** DEBIAN-CVE-2021-33797, GHSA-cm79-jwwm-5h7h

## What is CVE-2021-33797?

CVE-2021-33797 is a critical vulnerability in mujs, published on 17 Apr 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Buffer-overflow in jsdtoa.c in Artifex MuJS in versions 1.0.1 to 1.1.1. An integer overflow happens when js_strtod() reads in floating point exponent, which leads to a buffer overflow in the pointer *d.

Weakness: CWE-190 (Integer Overflow or Wraparound), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2021-33797?

It affects 1 product.


Products: Artifex Mujs.

## How do I fix CVE-2021-33797?

Upgrade to a fixed version.

## Is CVE-2021-33797 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-33797 exists.

## Other vulnerabilities in mujs

- [CVE-2021-33796](https://insights.sbomify.com/CVE-2021-33796/): Use after free in MuJS (critical 10.0)
- [CVE-2021-45005](https://insights.sbomify.com/CVE-2021-45005/): Memory corruption in n/a (critical 9.8)
- [CVE-2019-12798](https://insights.sbomify.com/CVE-2019-12798/): Integer overflow in n/a (critical 9.8)
- [CVE-2019-11411](https://insights.sbomify.com/CVE-2019-11411/): Memory corruption in n/a (critical 9.8)
- [CVE-2016-10133](https://insights.sbomify.com/CVE-2016-10133/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-33797 and fix it if it is affected.

What it is: CVE-2021-33797 is a critical vulnerability in mujs, published on 17 Apr 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-33797 exists.

Affected product: mujs. 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-2021-33797/ (Markdown: https://insights.sbomify.com/CVE-2021-33797/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-33797
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-33797
- OSV: https://osv.dev/vulnerability/CVE-2021-33797

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-33797/
Summaries are generated and may contain mistakes; the official description above is the record.