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Case File

CVE-2021-21321

CRITICAL · CVSS 10 EPSS 1.82% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-03-02 · Last synced 2026-08-04

CyberRota Analysis

AI analysis pending.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links
github.com ↗ github.com ↗

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2021-21321
Severity
CRITICAL
CVSS
10
EPSS
1.82%

Original NVD Description

fastify-reply-from is an npm package which is a fastify plugin to forward the current http request to another server. In fastify-reply-from before version 4.0.2, 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 4.0.2.