PatchSiren cyber security CVE debrief

CVE-2026-83917 Microsoft CVE debrief

A use-after-free vulnerability in Windows ALPC allows an authorized attacker to elevate privileges locally. Multiple Windows versions are affected, including Windows 10, Windows 11, and Windows Server. Microsoft has released a patch for this vulnerability. The vulnerability, known as CVE-2026-83917, is a high-severity issue that can be exploited locally. Affected versions include multiple Windows 10, Windows 11, and Windows Server releases. Immediate patching is recommended, especially for systems with high-risk exposure.

Vendor: Microsoft
Product: Windows 10 Version 1809
CVSS: HIGH 7
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-10-13
Original CVE updated: 2026-10-13
Advisory published: 2026-10-13
Advisory updated: 2026-10-13

Who should care

System administrators and security teams responsible for Windows systems, especially those with high-risk exposure, should prioritize patching affected versions to prevent local privilege escalation attempts.

Why it matters

CVE-2026-83917 is a high-severity vulnerability in Windows ALPC that allows authorized attackers to elevate privileges locally. Affected versions include multiple Windows 10, Windows 11, and Windows Server releases. Immediate patching is recommended, especially for systems with high-risk exposure.

Verify patch deployment for affected Windows versions to prevent exploitation
Assess system exposure and prioritize patching for high-risk systems
Monitor for potential local privilege escalation attempts

Technical summary

The vulnerability, CVE-2026-83917, is a use-after-free issue in Windows ALPC that allows an authorized attacker to elevate privileges locally. This affects multiple Windows versions, including Windows 10 Version 1809, Windows 10 Version 21H2, Windows 10 Version 22H2, Windows 11 version 23H2, Windows 11 Version 23H2, Windows 11 Version 24H2, Windows 11 Version 25H2, Windows 11 version 26H1, Windows 11 Version 26H2, Windows Server 2019, Windows Server 2019 (Server Core installation), Windows Server 2022, Windows Server 2025, and Windows Server 2025 (Server Core installation). Microsoft has released patches for these affected versions.

Defensive priority

Apply patches immediately for affected Windows versions, especially on systems with high-risk exposure.

Recommended defensive actions

Apply patches for affected Windows 10, Windows 11, and Windows Server versions
Verify system exposure and prioritize patching for high-risk systems
Monitor for potential local privilege escalation attempts

Evidence notes

The CVE Program and NVD provide official records of this vulnerability. Microsoft's advisory confirms the patch. Affected versions and patches are detailed in the source corpus.

Sources and references

Verified primary and authoritative sources

CVE-2026-83917 CVE Program record
Publisher, destination, and source semantics verified

URL: https://www.cve.org/CVERecord?id=CVE-2026-83917

CVE Program - Official CVE Program record with source-provided CVE metadata.
CVE-2026-83917 NVD vulnerability detail
Publisher, destination, and source semantics verified

URL: https://nvd.nist.gov/vuln/detail/CVE-2026-83917

NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Windows ALPC Elevation of Privilege Vulnerability
Unverified legacy reference

URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/83xxx/CVE-2026-83917.json

cve_program_cvelist_v5
Source reference
Unverified legacy reference

URL: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83917

Supplemental source - vendor-advisory, patch

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.