Security readout for executives and security teams
Plain-English summary
Attackers who can reach an affected vCenter Server over HTTPS may take complete control of its underlying operating system without credentials or user interaction. Because vCenter commonly manages broad virtual infrastructure, compromise could create significant operational, confidentiality, and integrity impact.
Executive priority
Treat this as an emergency remediation item. Prioritize exposed and business-critical vCenter systems, confirm upgrades promptly, and investigate potentially vulnerable systems because exploitation is documented and successful compromise grants unrestricted host-level privileges.
Technical view
CVE-2021-21972 is a vSphere Client HTML5 plugin path-traversal vulnerability, classified as CWE-22. Network access to TCP port 443 can permit unauthenticated command execution with unrestricted operating-system privileges. It affects specified older releases of VMware vCenter Server and VMware Cloud Foundation.
Likely exposure
Exposure exists where affected vCenter Server or Cloud Foundation versions are deployed and their port 443 is reachable by a malicious actor. Internet accessibility increases risk, but reachable internal management interfaces also require attention. The supplied evidence does not quantify exposed installations.
Exploitation context
CISA lists CVE-2021-21972 in its Known Exploited Vulnerabilities catalog, supporting active exploitation in the wild. The supplied sources do not identify current campaigns, attacker groups, exploitation frequency, or confirmed victim impact.
Researcher notes
The CVSS 3.1 score is 9.8 with network reachability, low complexity, no privileges, and no user interaction. The supplied bundle identifies CWE-22 but does not provide plugin internals, indicators of compromise, exploit prerequisites beyond port 443 reachability, or forensic artifacts.
Mitigation direction
- Upgrade vCenter 7.x to 7.0 U1c or later.
- Upgrade vCenter 6.7 to 6.7 U3l or later.
- Upgrade vCenter 6.5 to 6.5 U3n or later.
- Upgrade Cloud Foundation 4.x to 4.2 or later.
- Upgrade Cloud Foundation 3.x to 3.10.1.2 or later.
- Restrict port 443 exposure while following current vendor guidance.
Validation and detection
- Inventory all vCenter Server and VMware Cloud Foundation versions.
- Identify which networks and users can reach port 443.
- Confirm installed builds meet or exceed the stated fixed releases.
- Review relevant vCenter and operating-system telemetry for unexplained commands or changes.
- Verify network controls prevent unnecessary access to management interfaces.
Public sources used
The source record changed after analysis: Material source record changed after analysis.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-21972 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- ADP timelineCISA-ADP
CVE-2021-21972 added to CISA KEV
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2021-11-03T00:00:00.000Z: CVE-2021-21972 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- https://www.vmware.com/security/advisories/VMSA-2021-0002.htmlCVE reference, vmware · x_refsource_CONFIRM
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21972CVE reference, CISA-ADP · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.