Security readout for executives and security teams
Plain-English summary
A memory-safety flaw in Windows Hyper-V can let an unauthorized local attacker gain elevated privileges. Successful exploitation could compromise confidentiality, integrity, and availability across a security boundary. The supplied data identifies Windows 11 23H2 and Windows Server 2022 as affected, making Hyper-V hosts and other systems using this component the priority.
Executive priority
Treat this as an urgent patching priority because exploitation could produce complete high-impact compromise without prior privileges or user interaction. Focus first on critical Hyper-V infrastructure and systems accessible to untrusted local users. Current evidence does not establish active exploitation, so urgency comes from technical severity and exposure, not confirmed attacks.
Technical view
CVE-2026-40402 is a use-after-free vulnerability, classified as CWE-416, in Windows Hyper-V. Its CVSS 3.1 score is 9.3: local access, low complexity, no privileges or user interaction, changed scope, and high impact to confidentiality, integrity, and availability. The source bundle does not document exploitation mechanics or prerequisites beyond local access.
Likely exposure
Potential exposure includes Windows 11 version 23H2 build 10.0.22631.0 and Windows Server 2022 build 10.0.20348.0. Prioritize systems where Hyper-V is installed or used. The supplied sources do not clarify whether additional builds, configurations, or disabled Hyper-V installations are affected.
Exploitation context
The CVSS vector indicates local attack access, low complexity, no prior privileges, and no user interaction. KEV status is false, and exploit maturity is unproven in the supplied data. Therefore, there is no source-supported evidence here of active exploitation or a public working exploit.
Researcher notes
The record identifies CWE-416 and a changed-scope CVSS vector but provides no root-cause detail, affected Hyper-V subsystem, attack preconditions beyond local access, indicators, or exploit evidence. Duplicate Windows 11 23H2 entries appear in the supplied affected list. Validate definitive version ranges and update applicability against Microsoft’s advisory.
Mitigation direction
- Review Microsoft’s CVE advisory for the applicable security update and deployment requirements.
- Patch affected Windows 11 23H2 and Windows Server 2022 systems according to Microsoft guidance.
- Prioritize internet-facing, shared, or high-value Hyper-V hosts within normal emergency-change controls.
- Restrict local access to affected systems until remediation is confirmed.
- Monitor Microsoft guidance for revised affected-version or mitigation information.
Validation and detection
- Inventory the listed Windows versions and determine where Hyper-V is installed or active.
- Compare installed build and update levels with Microsoft’s CVE advisory.
- Confirm the applicable security update installed successfully on each affected system.
- Reboot where Microsoft’s update guidance requires it, then verify update status again.
- Review endpoint and host telemetry for unexplained privilege changes or Hyper-V-related crashes.
Public sources used
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-416: 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 lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-40402 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
- 9.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
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:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C2.56microsoftVulnerability scoring details
Base CVSS 3.1 score
9.3CriticalVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
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
- Windows Hyper-V Elevation of Privilege VulnerabilityCVE reference, microsoft · vendor-advisory, patch
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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.