Windows Projected File System: Information disclosure through TOCTOU race condition
Summary
A time-of-check time-of-use (TOCTOU) race condition in the Windows Projected File System (ProjFS) allows an authorized local user to read information they should not be able to access. Exploitation requires local access, a low-privileged account and a high attack complexity. The impact is limited to confidentiality; integrity and availability are not affected. Microsoft rates the flaw at CVSS 4.7 (Medium).
Affected
- Windows 10 Version 1809 and Windows Server 2019 (including Server Core): 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 and Windows 11 Version 25H2: builds before 10.0.26100.9974 and 10.0.26200.9974 respectively
- Windows 11 Version 26H1: builds before 10.0.28000.3501
- Windows 11 Version 26H2: builds before 10.0.26300.9974
- Windows Server 2022: builds before 10.0.20348.5870
- Windows Server 2025 (including Server Core): builds before 10.0.26100.33822
Note: Version thresholds from third-party aggregators conflict with the CVE record; verify on the MSRC page.
Fixed in
- Install the Microsoft security update released with the November 2026 Patch Tuesday for the affected edition.
- Fixed builds per the CVE record: see the affected builds above (the first build at or above each threshold is the fix).
Workaround
Unknown. No workaround or mitigation is documented in the sources reviewed. Installing the update is the practical fix.
Exploitation
- No evidence of exploitation in the wild.
- No public proof-of-concept found in a limited search.
- CISA SSVC: exploitation none, not automatable, partial technical impact.
Our recommendation
- Include this update in the regular November 2026 patch cycle on all affected Windows clients and servers.
- Prioritise multi-user systems such as terminal servers, shared file servers and developer machines.
- Install the related Projected File System fixes CVE-2026-112799 and CVE-2026-108414 in the same cycle.
- Verify the exact fixed builds and KB numbers on the MSRC page before rollout.
- Monitor for public proof-of-concept code or exploitation reports.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – Windows Projected File System
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5131085, KB5131096, KB5131090, KB5131087, KB5132061, KB5132043
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-113764 msrc.microsoft.com
- CVE Record CVE-2026-113764 (CNA: Microsoft) www.cve.org
- Rapid7: Patch Tuesday November 2026 www.rapid7.com
- Cybersecuritynews: Microsoft November 2026 Patch Tuesday cybersecuritynews.com
- Senserva: KB5131085 (Windows Server 2019 / 1809) senserva.com
- MSRC: CVE-2026-108414 (related ProjFS flaw) msrc.microsoft.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, 20:54.
Original description (NVD)
Time-of-check time-of-use (toctou) race condition in Windows Projected File System allows an authorized attacker to disclose information 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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