# CVE-2021-25943: Prototype pollution in 101

> Prototype pollution in the 101 npm package allows attackers to cause denial of service and potentially execute remote code.

- **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:** No
- **Published:** 14 May 2021
- **Updated:** 30 Apr 2025
- **Also known as:** GHSA-cwcx-rxgc-cmw3

## What is CVE-2021-25943?

CVE-2021-25943 is a critical code injection vulnerability in 101, published on 14 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Prototype pollution vulnerability in '101' versions 1.0.0 through 1.6.3 allows an attacker to cause a denial of service and may lead to remote code execution.

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

## Which versions are affected by CVE-2021-25943?

2 open source packages ship an affected version, including 101. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `101` | npm | From 1.0.0 to 1.6.3 | None |
| `101` | npm | From 1.0.0 to 1.6.3 | None |

Products: 101 Project 101.

## How do I fix CVE-2021-25943?

No fix has been published for CVE-2021-25943 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-25943 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-25943 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-25943 and fix it if it is affected.

What it is: CVE-2021-25943 is a critical code injection vulnerability in 101, published on 14 May 2021. 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-2021-25943 exists.

Affected packages and fixed versions:
- 101 (npm): affected from 1.0.0 up to 1.6.3; no fix listed
- 101 (npm): affected from 1.0.0 up to 1.6.3; no fix listed

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-2021-25943/ (Markdown: https://insights.sbomify.com/CVE-2021-25943/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-25943
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-25943
- OSV: https://osv.dev/vulnerability/CVE-2021-25943

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-25943/
Summaries are generated and may contain mistakes; the official description above is the record.