Security readout for executives and security teams
Plain-English summary
This flaw lets an unauthenticated attacker who can reach vCenter Server on port 443 run commands with unrestricted operating-system privileges. Compromise could expose or disrupt centralized virtual infrastructure management. The vulnerable Virtual SAN Health Check plug-in is enabled by default.
Executive priority
Treat as an immediate remediation priority because exploitation is documented, authentication is unnecessary, and successful compromise grants unrestricted host operating-system privileges. Prioritize reachable management servers and investigate potentially exposed systems rather than assuming patching alone excludes earlier compromise.
Technical view
CVE-2021-21985 is an input-validation failure in the vSphere Client's Virtual SAN Health Check plug-in. It enables network-based, low-complexity remote code execution without privileges or user interaction. CVSS 3.1 rates it 9.8, with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure exists where affected vCenter Server or VMware Cloud Foundation versions are deployed and attackers can reach vCenter Server port 443. Internet exposure increases concern, but internal network access is also sufficient. The supplied evidence does not identify individual exposed organizations.
Exploitation context
CISA includes CVE-2021-21985 in its Known Exploited Vulnerabilities catalog, supporting active exploitation in the wild. The supplied sources do not establish current exploitation volume, specific threat actors, targeting patterns, or compromise indicators.
Researcher notes
The supplied classification identifies CWE-20, CWE-470, and CWE-918. The evidence establishes default plug-in enablement, port 443 reachability, unauthenticated command execution, affected version boundaries, and KEV status. It does not provide reliable exploit-chain details, indicators, or attribution.
Mitigation direction
- Update vCenter 7.x to 7.0 U2b or later.
- Update vCenter 6.7 to 6.7 U3n or later.
- Update vCenter 6.5 to 6.5 U3p or later.
- Update Cloud Foundation 4.x to 4.2.1 or later.
- Update Cloud Foundation 3.x to 3.10.2.1 or later.
- Restrict port 443 access to trusted management networks while remediation is pending.
Validation and detection
- Inventory all vCenter Server and VMware Cloud Foundation deployments.
- Compare installed versions against every affected-version boundary.
- Confirm port 443 reachability from untrusted and ordinary internal networks.
- Verify applicable updates completed successfully on each instance.
- Consult vendor guidance for available compromise indicators and post-update checks.
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-20: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupCWE-470: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupCWE-918: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. 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-2021-21985 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-2021-21985 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-2021-21985 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- https://www.vmware.com/security/advisories/VMSA-2021-0010.htmlCVE reference, vmware · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21985CVE 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 Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Server-Side Request Forgery (SSRF)
Server-Side Request Forgery (SSRF) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.