# @fastify/middie (npm) vulnerabilities

4 known vulnerabilities (1 critical, 3 high), with the versions each affects and the releases that fix them.

## At a glance

- Latest release: 9.3.6 (Oct 20, 2026): no advisory affects it
- Newest unaffected release: 9.3.6 (Oct 20, 2026), the latest release
- Weekly downloads: 2.7M
- Dependents: 157
- Releases: 22 since 8.0.0 (Jun 6, 2022)
- Registry: https://www.npmjs.com/package/@fastify/middie
- Releases read: Nov 8, 2026

## Version timeline

Affected versions per advisory, in version order:

- CVE-2026-33804: 8.0.0 to 9.3.1 (9.3.2 is outside it)
- CVE-2026-6270: 8.0.0 to 9.3.1 (9.3.2 is outside it)
- CVE-2026-2880: 8.0.0 to 9.1.0 (9.2.0 is outside it)
- CVE-2026-22031: 8.0.0 to 9.0.3 (9.1.0 is outside it)

## Advisories (4)

### [CVE-2026-33804](https://cve.now/CVE-2026-33804): @fastify/middie vulnerable to middleware bypass via deprecated ignoreDuplicateSlashes option

- Severity: High 7.4
- Published: Apr 16, 2026
- Affected: fixed in 9.3.2.
- Fixed in 9.3.2 (released Apr 16, 2026, the day of disclosure).
- The latest release, 9.3.6, is not affected.
- 21% of @fastify/middie downloads last week were affected versions (611.8K).

### [CVE-2026-6270](https://cve.now/CVE-2026-6270): @fastify/middie vulnerable to middleware authentication bypass in child plugin scopes

- Severity: Critical 9.1
- Published: Apr 16, 2026
- Affected: fixed in 9.3.2.
- Fixed in 9.3.2 (released Apr 16, 2026, the day of disclosure).
- The latest release, 9.3.6, is not affected.
- 21% of @fastify/middie downloads last week were affected versions (611.8K).

### [CVE-2026-2880](https://cve.now/CVE-2026-2880): @fastify/middie has an improper path normalization vulnerability

- Severity: High 8.2
- Published: Feb 27, 2026
- Affected: fixed in 9.2.0.
- Fixed in 9.2.0 (released Feb 27, 2026, the day of disclosure).
- The latest release, 9.3.6, is not affected.
- 21% of @fastify/middie downloads last week were affected versions (605.2K).

### [CVE-2026-22031](https://cve.now/CVE-2026-22031): Fastify Middie Middleware Path Bypass

- Severity: High 8.4
- Published: Jan 19, 2026
- Affected: fixed in 9.1.0.
- Fixed in 9.1.0 (released Jan 3, 2026, 16 days before disclosure).
- The latest release, 9.3.6, is not affected.
- 21% of @fastify/middie downloads last week were affected versions (598.7K).

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