Threats / VMware / CVE-2021-21972
CVE-2021-21972
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
VMware vCenter Server vulnerability
VMware vCenter Server contains a remote code execution vulnerability in the vSphere Client plugin accessible over port 443, allowing unauthenticated network attackers to execute arbitrary commands with unrestricted privileges.
Verdict
Today item, not a backlog item.
Critical remote code execution vulnerability in widely deployed virtualization infrastructure. Active exploitation in the wild and association with ransomware campaigns indicates immediate threat to enterprise environments. Requires urgent patching.
CISA KEV Yes · 2021-11-033Ransomware use Flagged3EPSS 0.9957 (verify live)4Exploit Weaponized · public PoC5
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
327 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.9957 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: VMware, vCenter Server. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-23 Relative Path Traversal — weakness family: Path traversal / file.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I identify vCenter Server instances exposed on port 443 and send a crafted request to the vulnerable plugin.
Business
Attacker gains initial access to the virtualization management layer without authentication.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I execute arbitrary commands with unrestricted operating system privileges on the vCenter host.
Business
Complete compromise of the virtualization infrastructure enables lateral movement across all managed virtual machines.
3
Lateral reach — past segmentation narrative 3
Attacker
I deploy ransomware or persistence mechanisms across the hypervisor and connected guest systems.
Business
Enterprise suffers widespread service disruption, data encryption, and potential total loss of virtualized workloads.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05