Security readout for executives and security teams
Plain-English summary
A user who already has limited authorized access to an affected Windows system may exploit a timing flaw in Windows Management Services to gain higher privileges. Successful exploitation could allow extensive access to sensitive data, system changes, and service disruption. The attacker must act locally, and exploitation is rated technically difficult.
Executive priority
Treat as a high-priority patching issue, particularly for servers and shared endpoints. It is not remotely exploitable from the supplied evidence, reducing immediate perimeter risk, but it could turn an initial low-privilege foothold into broad system compromise. Track remediation through standard vulnerability-management reporting.
Technical view
CVE-2026-20867 is an improper-synchronization race condition in Windows Management Services. The associated weaknesses include race condition, double free, and use-after-free. CVSS 3.1 is 7.8: local access, low privileges, high complexity, no user interaction, changed scope, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure includes the listed Windows 10, Windows 11, Windows Server 2019, 2022, 23H2, and 2025 releases, including specified Server Core installations. Risk is greatest where untrusted or compromised low-privilege users can execute code locally. The supplied evidence does not define vulnerable configuration prerequisites beyond the listed products and versions.
Exploitation context
The attacker must already be authorized with low privileges and operate locally. Exploitation requires winning a race condition, reflected by high attack complexity, but needs no user interaction. This vulnerability is not identified as CISA KEV in the supplied bundle, and no cited evidence establishes active exploitation or public exploit availability.
Researcher notes
The supplied record identifies concurrent use of a shared resource without proper synchronization and maps CWE-362, CWE-415, and CWE-416. Exact affected components, timing conditions, vulnerable code paths, update identifiers, and detection artifacts are not provided. Safe validation should rely on version and update compliance rather than attempting exploitation in production.
Mitigation direction
- Review Microsoft's CVE update guide for the security update applicable to each affected Windows release.
- Prioritize updates on multi-user systems, servers, and endpoints where low-privilege code execution is possible.
- Apply normal least-privilege controls while updates are tested and deployed.
- Use vendor-supported releases and confirm update deployment through centralized endpoint management.
Validation and detection
- Inventory systems running the listed Windows client and server releases.
- Compare installed updates against Microsoft's guidance for CVE-2026-20867.
- Confirm applicable security updates installed successfully and survived reboot where required.
- Monitor privileged account creation, service changes, and unexpected elevation activity on exposed systems.
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-362: 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-415: 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-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-2026-20867 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
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:L/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:H/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C1.16microsoftVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:H/PR:L/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 Management Services 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.
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Double Free
Double Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.