Microsoft Windows 11 26H1: Information disclosure in Windows Composite Image File System
Summary
A local information disclosure flaw in the Windows Composite Image File System (CimFS) of Windows 11 version 26H1 allows an authorized attacker to read data they should not be able to access. The attacker needs an existing low-privilege local account and no user interaction is required. The issue has no integrity or availability impact and is not internet-exposed, but it matters most on shared multi-user systems.
Affected
- Microsoft Windows 11 version 26H1, builds 10.0.28000.0 before 10.0.28000.3501
- Other Windows versions are not listed in the CVE record.
Fixed in
- Build 10.0.28000.3501 and later, included in the November 2026 Patch Tuesday update (per the CVE record range; not yet verified against the MSRC advisory).
Workaround
- Unknown. No workaround found in the sources; check the MSRC advisory.
Exploitation
- Microsoft rates exploitation as less likely (CISA SSVC: Exploitation none, Automatable no, Technical Impact partial).
- No public disclosure and no known proof-of-concept exploit code.
- Not listed in CISA KEV.
Our recommendation
- Check whether any device runs Windows 11 26H1 below build 10.0.28000.3501 (for example with winver).
- Install the November 2026 cumulative update on those devices and confirm the build number.
- Prioritise multi-user systems such as terminal servers, shared workstations and file servers.
- Read the MSRC advisory for update-specific notes.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – Windows Composite Image File System
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows
- Updates (KB)
- KB5132059
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE record (Microsoft CNA) www.cve.org
- MSRC advisory msrc.microsoft.com
- Rapid7 Patch Tuesday, Nov 2026 www.rapid7.com
- Strix.ai www.strix.ai
- Patch Tuesday roundup www.anoopcnair.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, 16:53.
Original description (NVD)
Improper access control in Windows Composite Image 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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