Security readout for executives and security teams
Plain-English summary
A person who already has limited local access to an affected Windows device may be able to gain higher privileges. Successful exploitation could expose sensitive data, alter systems, or disrupt operations. The attack requires local access and high complexity, reducing—but not eliminating—risk.
Executive priority
Treat this as a high-priority patching issue, especially on sensitive servers and privileged workstations. It is not evidenced as an emergency internet-scale threat, but it can amplify damage after an attacker gains local access. Track remediation through verified update installation.
Technical view
CVE-2026-20923 is a use-after-free vulnerability in Windows Management Services. It permits local privilege elevation by an authorized low-privileged attacker without user interaction. CVSS 3.1 rates it 7.8, with high complexity, changed scope, and potentially high confidentiality, integrity, and availability impact.
Likely exposure
Exposure includes the listed Windows 10, Windows 11, Windows Server 2019, 2022, 23H2, and 2025 builds, including specified Server Core installations. Confirm applicability against Microsoft guidance because the bundle does not provide exact security-update or supersedence details.
Exploitation context
The supplied sources do not establish active exploitation, and the CVE is not identified as CISA KEV. Exploitation requires local access, low privileges, and high attack complexity, with no user interaction. It is most relevant after an attacker obtains an initial foothold or a malicious insider gains device access.
Researcher notes
The weakness is CWE-416 use-after-free. The vector is AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H. Public evidence supplied here does not identify exploitation techniques, affected component internals, patch identifiers, or active attacks. Researchers should rely on Microsoft’s advisory for build-specific applicability and remediation.
Mitigation direction
- Review Microsoft’s CVE advisory and apply the applicable security update.
- Prioritize shared servers, administrator workstations, and systems handling sensitive information.
- Restrict unnecessary local access while remediation is pending.
- Monitor Microsoft guidance for revised affected-build or update information.
Validation and detection
- Inventory Windows editions, versions, builds, and Server Core installations.
- Compare inventory results with Microsoft’s affected-product and security-update tables.
- Verify the applicable security update is installed successfully.
- Re-scan endpoints and investigate failed or pending update deployments.
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-2026-20923 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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.