Microsoft Windows: Local privilege escalation in Volume Shadow Copy
Summary
A race condition in the Windows Volume Shadow Copy Service (VSS) allows an authorized local attacker to elevate privileges. Microsoft states that a successful attacker could gain SYSTEM privileges. The attacker needs an existing low-privilege local account and must win a race condition, so the attack is not trivial.
Affected
- Windows 10 Version 1607 (builds before 10.0.14393.9688)
- Windows 10 Version 1809 (builds before 10.0.17763.9487)
- Windows 10 Version 21H2 (builds before 10.0.19044.7846)
- Windows 10 Version 22H2 (builds before 10.0.19045.7846)
- Windows 11 Version 23H2 (builds before 10.0.22631.7711)
- Windows 11 Version 24H2 (builds before 10.0.26100.9974)
- Windows 11 Version 25H2 (builds before 10.0.26200.9974)
- Windows 11 Version 26H1 (builds before 10.0.28000.3501)
- Windows 11 Version 26H2 (builds before 10.0.26300.9974)
- Windows Server 2016 incl. Server Core (builds before 10.0.14393.9688)
- Windows Server 2019 incl. Server Core (builds before 10.0.17763.9487)
- Windows Server 2022 (builds before 10.0.20348.5870)
Fixed in
- Windows 10 1607: 10.0.14393.9688
- Windows 10 1809: 10.0.17763.9487
- Windows 10 21H2: 10.0.19044.7846
- Other products: fixed builds are listed in the Microsoft advisory; verify them there before rollout. Third-party data for other builds is not confirmed.
Workaround
Unknown.
Exploitation
- Microsoft marks the vulnerability as not exploited in the wild.
- Microsoft rates exploit code maturity as Unproven; no public proof of concept was found.
- CVSS 3.1 base score 7.0 (AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).
Our recommendation
- Install the November 2026 cumulative update on all affected Windows 10, Windows 11 and Windows Server systems. Confirm the exact KB per build in the Microsoft Security Update Guide.
- Prioritise multi-user systems such as terminal, RDP and shared file servers.
- Until patched, restrict local and Remote Desktop logon to necessary users, remove unneeded local accounts and monitor for unusual VSS service activity.
- Treat this as a regular patch-cycle item rather than an emergency, unless exploitation becomes known.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Volume Shadow Copy
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide (CVE-2026-105017) msrc.microsoft.com
- CVE Record CVE-2026-105017 www.cve.org
- Rapid7 Patch Tuesday November 2026 www.rapid7.com
- Strix CVE-2026-105017 (third party) www.strix.ai
- KB5131090 (third party) senserva.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 11 Nov 2026, 09:51.
Original description (NVD)
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Volume Shadow Copy allows an authorized attacker to elevate privileges locally.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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