---
cve: "CVE-2021-21322"
severity: "CRITICAL"
cvss: 10.0
epss: "1.6%"
vendor: "fastify"
kev: false
exploited: false
published: "2021-03-02 04:15:12"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-06T11:53:22+02:00"
---

# CVE-2021-21322

> 10.0 CRITICAL · 🧪 PoC

## Beschreibung

fastify-http-proxy is an npm package which is a fastify plugin for proxying your http requests to another server, with hooks. By crafting a specific URL, it is possible to escape the prefix of the proxied backend service. If the base url of the proxied server is `/pub/`, a user expect that accessing `/priv` on the target service would not be possible. In affected versions, it is possible. This is fixed in version 4.3.1.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- 33dba25c32af41beafc3cbb7139e2708bfda26db (Commit)
- 02d9b43c770aa16bc44470edecfaeb7c17985016 (Commit)

## Referenzen

- <https://github.com/fastify/fastify-http-proxy/security/advisories/GHSA-c4qr-gmr9-v23w>
- <https://www.npmjs.com/package/fastify-http-proxy>
- <https://github.com/fastify/fastify-http-proxy/commit/02d9b43c770aa16bc44470edecfaeb7c17985016>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2021-21322) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_