HOMEVULNERABILITIESCVE-2021-21322
CRITICAL

CVE-2021-21322

CWE-20Published: March 2, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2021-21322 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

fastify-http-proxy_project1 product(s)
fastify-http-proxy
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
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Official Patches & Advisories

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

All References (6)

→
https://github.com/fastify/fastify-http-proxy/commit/02d9b43c770aa16bc44470edecfaeb7c17985016Patch · Third Party Advisory
→
https://github.com/fastify/fastify-http-proxy/security/advisories/GHSA-c4qr-gmr9-v23wThird Party Advisory
→
https://www.npmjs.com/package/fastify-http-proxyProduct · Third Party Advisory
→
https://github.com/fastify/fastify-http-proxy/commit/02d9b43c770aa16bc44470edecfaeb7c17985016Patch · Third Party Advisory
→
https://github.com/fastify/fastify-http-proxy/security/advisories/GHSA-c4qr-gmr9-v23wThird Party Advisory
→
https://www.npmjs.com/package/fastify-http-proxyProduct · Third Party Advisory

Quick Facts

CVE IDCVE-2021-21322
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-20
CISA KEVNo
Affected1 vendor(s)
PublishedMar 2, 2021

Related CVEs (CWE-20)

CVE-2011-0285
10.0
CVE-2011-1018
10.0
CVE-2020-13753
10.0
CVE-2008-6826
10.0
CVE-2021-23279
10.0
CVE-2008-4509
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-21322 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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