HOMEVULNERABILITIESCVE-2021-21986
CRITICAL

CVE-2021-21986

CWE-306Published: May 26, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

The vSphere Client (HTML5) contains a vulnerability in a vSphere authentication mechanism for the Virtual SAN Health Check, Site Recovery, vSphere Lifecycle Manager, and VMware Cloud Director Availability plug-ins. A malicious actor with network access to port 443 on vCenter Server may perform actions allowed by the impacted plug-ins without authentication.

NVD Source

Technical Analysis

CVE-2021-21986 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

VMware2 product(s)
vcenter servercloud foundation
Source: NVD CPE · 4 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
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttp://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.html
ADVISORYhttps://www.vmware.com/security/advisories/VMSA-2021-0010.html
ADVISORYhttp://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.html
ADVISORYhttps://www.vmware.com/security/advisories/VMSA-2021-0010.html

All References (4)

→
http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.htmlThird Party Advisory · VDB Entry
→
https://www.vmware.com/security/advisories/VMSA-2021-0010.htmlVendor Advisory
→
http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.htmlThird Party Advisory · VDB Entry
→
https://www.vmware.com/security/advisories/VMSA-2021-0010.htmlVendor Advisory

Quick Facts

CVE IDCVE-2021-21986
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-306
CISA KEVNo
Affected1 vendor(s)
PublishedMay 26, 2021

Related CVEs (CWE-306)

CVE-2025-41656
10.0
CVE-2026-10577
10.0
CVE-2020-26829
10.0
CVE-2025-55108
10.0
CVE-2026-56163
10.0
CVE-2026-20223
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-21986 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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