# CVE-2021-36535: Memory corruption in n/a

> Remote attackers can cause denial of service in Cesanta mJS by submitting crafted JavaScript files that trigger a buffer overflow.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Feb 2023
- **Updated:** 26 Mar 2025
- **Also known as:** GHSA-9mr9-jp9j-332h

## What is CVE-2021-36535?

CVE-2021-36535 is a medium-severity memory corruption vulnerability in Cesanta Mjs, published on 3 Feb 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Buffer Overflow vulnerability in Cesanta mJS 1.26 allows remote attackers to cause a denial of service via crafted .js file to mjs_set_errorf.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-36535?

It affects 1 product.


Products: Cesanta Mjs.

## How do I fix CVE-2021-36535?

No fix has been published for CVE-2021-36535 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-36535 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-36535 exists.

## Other vulnerabilities in Cesanta Mjs

- [CVE-2023-50044](https://insights.sbomify.com/CVE-2023-50044/): Memory corruption in n/a (critical 9.8)
- [CVE-2023-43338](https://insights.sbomify.com/CVE-2023-43338/): Memory corruption in n/a (critical 9.8)
- [CVE-2021-46509](https://insights.sbomify.com/CVE-2021-46509/): Denial of service in n/a (high 7.8)
- [CVE-2021-46513](https://insights.sbomify.com/CVE-2021-46513/): Memory corruption in n/a (high 7.8)
- [CVE-2021-46518](https://insights.sbomify.com/CVE-2021-46518/): Memory corruption in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-36535 and fix it if it is affected.

What it is: CVE-2021-36535 is a medium-severity memory corruption vulnerability in Cesanta Mjs, published on 3 Feb 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-36535 exists.

Affected product: Cesanta Mjs. 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-2021-36535/ (Markdown: https://insights.sbomify.com/CVE-2021-36535/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-36535
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-36535
- OSV: https://osv.dev/vulnerability/CVE-2021-36535

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-36535/
Summaries are generated and may contain mistakes; the official description above is the record.