critical Known exploitedREV. 01

CVE-2021-21972VMware vCenter — Unauthenticated Upload in a vSphere Plugin

A vCenter plugin accepts uploads without authentication, letting anyone who can reach the management port write a file and run code on the server that controls the estate.

YOUR NEXT MOVE

Apply VMware's patch for vCenter Server, and check the plugin directories for files written while it was exposed.

Read the risk

THE VITAL STATS
CVSS score
9.8/ 10
CVSS v3.1
EPSS probability
100%
Likelihood of exploitation
Attack complexity
Low
Conditions needed to exploit
Known exploited
Yes — CISA KEV
CVE published
2021-02-24
Added to KEV
2021-11-03
Exploit published
Yes
Confidence
high
Kill chain
initial access
MITRE ATT&CK
T1190, T1083
Severity
critical

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

Attacker needsNetwork access to the vCenter management port

Behind the card

5 REFERENCES
Field-level provenanceTRACE THE SOURCES +

Which source supports each field, when it was retrieved, and who extracted it.

FieldsSourceRetrievedExtractorConfidence
cvss, exploitation.attack_complexity, exploitation.exploit_available, references, published_atnvd.nist.gov2026-08-07scrty-crds-pipeline/0.1high
exploitation.known_exploited, exploitation.kev_addedcisa.gov2026-08-07scrty-crds-pipeline/0.1high
epssapi.first.org2026-08-07scrty-crds-pipeline/0.1high
title, summary, severity, remediation, mitre_attack, kill_chain, recommended_action, confidence, tags, exploitation.prerequisitesnvd.nist.gov2026-08-07claude-codehigh

Printing history

THE RECORD
  1. r1Initial base card

First printing. This card has not been reprinted since publication.

crds:cve-2021-21972 · CRDS 0.1 · Issued 2026-08-07