Security readout for executives and security teams
This flaw affects VMware ESXi OpenSLP. An attacker already on the same network segment as a vulnerable host could reach port 427 and potentially run code on the hypervisor. Because ESXi hosts underpin many workloads, compromise could threaten confidentiality, integrity, and availability across virtualized systems. Organizations running older VMware ESXi 7.0, 6.7, or 6.5 builds, or VMware Cloud Foundation 4.x before 4.2 and 3.x, are the likely exposure group. Risk is highest where ESXi port 427 is reachable from shared management, server, or adjacent network segments. Treat this as high priority for virtualization environments. It is not listed as KEV in the bundle, but the potential impact is severe because successful exploitation could affect the hypervisor layer supporting many systems. Mitigation focus: Apply the VMware fixed ESXi builds or later versions named in VMSA-2021-0002.; Upgrade VMware Cloud Foundation according to VMware guidance for affected 4.x and 3.x releases.; Restrict access to ESXi port 427 to trusted management networks only..
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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
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CWE-787: 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 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-2021-21974 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
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/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.
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:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H2.85.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:A/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.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
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.zerodayinitiative.com/advisories/ZDI-21-250/CVE reference, vmware · x_refsource_MISC
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.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.