CVE-2021-21985

Act now ● On CISA KEV — actively exploited used in ransomware

Actively exploited — on the CISA KEV list.

CVSS base

9.8 CRITICAL

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

EPSS — probability of exploitation (30 days)

100.0%

100.0th percentile

CISA KEV

Listed

Added 2021-11-03 · patch by 2021-11-17

Weakness / dates

CWE-20

Published 2021-05-26 · modified 2026-08-12

CVSS breakdown

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

Attack Vector	N	Network
Attack Complexity	L	Low
Privileges Required	N	None
User Interaction	N	None
Scope	U	Unchanged
Confidentiality	H	High
Integrity	H	High
Availability	H	High

Timeline

2021-05-26 — Published (NVD)
2021-11-03 — Added to CISA KEV (actively exploited)
2021-11-17 — CISA patch-by deadline
2026-08-12 — Last modified (NVD)

Description

The vSphere Client (HTML5) contains a remote code execution vulnerability due to lack of input validation in the Virtual SAN Health Check plug-in which is enabled by default in vCenter Server. A malicious actor with network access to port 443 may exploit this issue to execute commands with unrestricted privileges on the underlying operating system that hosts vCenter Server.

Affected

vmware

References

Official: NVD · CVE.org