# @fastify/express (npm) vulnerabilities

3 known vulnerabilities (2 critical, 1 high), with the versions each affects and the releases that fix them.

## At a glance

- Latest release: 4.0.9 (Oct 27, 2026): no advisory affects it
- Newest unaffected release: 4.0.9 (Oct 27, 2026), the latest release
- Weekly downloads: 108.1K
- Dependents: 16
- Releases: 21 since 1.0.0 (Apr 27, 2022)
- Registry: https://www.npmjs.com/package/@fastify/express
- Releases read: Nov 8, 2026

## Version timeline

Affected versions per advisory, in version order:

- CVE-2026-33807: 1.0.0 to 4.0.4 (4.0.5 is outside it)
- CVE-2026-33808: 1.0.0 to 4.0.4 (4.0.5 is outside it)
- CVE-2026-22037: 1.0.0 to 4.0.2 (4.0.3 is outside it)

## Advisories (3)

### [CVE-2026-33807](https://cve.now/CVE-2026-33807): @fastify/express vulnerable to middleware path doubling causing authentication bypass in child plugin scopes

- Severity: Critical 9.1
- Published: Apr 15, 2026
- Affected: fixed in 4.0.5.
- Fixed in 4.0.5 (released Apr 15, 2026, the day of disclosure).
- The latest release, 4.0.9, is not affected.
- 53% of @fastify/express downloads last week were affected versions (66.2K).

### [CVE-2026-33808](https://cve.now/CVE-2026-33808): @fastify/express vulnerable to middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)

- Severity: Critical 9.1
- Published: Apr 15, 2026
- Affected: fixed in 4.0.5.
- Fixed in 4.0.5 (released Apr 15, 2026, the day of disclosure).
- The latest release, 4.0.9, is not affected.
- 53% of @fastify/express downloads last week were affected versions (66.2K).

### [CVE-2026-22037](https://cve.now/CVE-2026-22037): @fastify/express vulnerable to Improper Handling of URL Encoding (Hex Encoding)

- Severity: High 8.4
- Published: Jan 19, 2026
- Affected: fixed in 4.0.3.
- Fixed in 4.0.3 (released Jan 5, 2026, 14 days before disclosure).
- The latest release, 4.0.9, is not affected.
- 50% of @fastify/express downloads last week were affected versions (62.8K).

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