# CVE-2020-7743: Prototype Pollution

> Prototype pollution in mathjs allows attackers to modify object prototypes, potentially leading to code execution or security bypasses.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Oct 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-x2fc-mxcx-w4mf

## What is CVE-2020-7743?

CVE-2020-7743 is a high-severity vulnerability in mathjs, published on 13 Oct 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The package mathjs before 7.5.1 are vulnerable to Prototype Pollution via the deepExtend function that runs upon configuration updates.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2020-7743?

2 open source packages ship an affected version, including mathjs. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mathjs` | npm | All versions | 7.5.1 |
| `mathjs` | npm | All versions | 7.5.1 |

Products: Mathjs Mathjs.

## How do I fix CVE-2020-7743?

Upgrade mathjs to 7.5.1 or later.

## Is CVE-2020-7743 being exploited?

There is no known exploitation of CVE-2020-7743 in the wild and no public exploit code.

## Other vulnerabilities in mathjs

- [CVE-2026-41139](https://insights.sbomify.com/CVE-2026-41139/): Unsafe array index getter in mathjs (high 8.8)
- [CVE-2026-40897](https://insights.sbomify.com/CVE-2026-40897/): Math.js: Unsafe object property setter in mathjs (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-7743 and fix it if it is affected.

What it is: CVE-2020-7743 is a high-severity vulnerability in mathjs, published on 13 Oct 2020. 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-2020-7743 in the wild and no public exploit code.

Affected packages and fixed versions:
- mathjs (npm): affected all versions; fixed in 7.5.1
- mathjs (npm): affected all versions; fixed in 7.5.1

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-2020-7743/ (Markdown: https://insights.sbomify.com/CVE-2020-7743/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-7743
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-7743
- OSV: https://osv.dev/vulnerability/CVE-2020-7743

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-7743/
Summaries are generated and may contain mistakes; the official description above is the record.