Microsoft Windows: Information disclosure in Mailslot File System
Summary
A local, authorized attacker can read information from the Windows Mailslot File System because of an uninitialized resource (CWE-908). The flaw affects supported Windows 10, Windows 11 and Windows Server releases. Exploitation requires a valid low-privilege local account, and the impact is limited to confidentiality.
Affected
- Windows 10 Version 1607 and Windows Server 2016 (including Server Core): before 10.0.14393.9688
- Windows 10 Version 1809 and Windows Server 2019 (including Server Core): before 10.0.17763.9487
- Windows 10 Version 21H2: affected, fixed build not shown in the CVE record
- Windows 10 Version 22H2: affected, fixed build not confirmed
- Windows 11 Version 23H2: affected, fixed build 10.0.22631.7711 per CVE record (secondary data, unverified)
- Windows 11 Version 24H2, 25H2 and 26H2: affected, listed fixed builds 10.0.26100.9974, 10.0.26200.9974 and 10.0.26300.9974 (one source gives 10.0.26100.33822 for 24H2; unverified)
- Windows 11 Version 26H1: before 10.0.28000.3501
- Windows Server 2022: before 10.0.20348.5870
- Windows Server 2025: not listed in the CVE record; third-party summary says it is covered by KB5131080 (unverified)
Fixed in
Security update released on November 10, 2026 for each affected product. Exact fixed builds: see the MSRC page. Unknown for Windows 10 21H2 and 22H2 in the verified sources.
Workaround
Unknown. No workaround or mitigation was found in the sources.
Exploitation
- Not known to be exploited in the wild; CISA SSVC lists exploitation as none
- Rapid7 rates exploitation as less likely and reports no public disclosure
- No public proof of concept known
Our recommendation
- Install the November 2026 Windows security update on all affected systems
- Prioritise terminal servers, shared workstations and file servers with many user accounts
- Review which users have local logons on multi-user systems
- Apply on single-user workstations in the normal monthly patch cycle
- Check the MSRC page for exact builds of your releases
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – Mailslot 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)
- KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-105537 msrc.microsoft.com
- CVE Record CVE-2026-105537 www.cve.org
- Rapid7 Patch Tuesday November 2026 www.rapid7.com
- Senserva summary KB5131080 senserva.com
- BleepingComputer: Microsoft November 2026 Patch Tuesday www.bleepingcomputer.com
- Strix.ai CVE-2026-105537 (secondary data) www.strix.ai
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, 17:01.
Original description (NVD)
Use of uninitialized resource in Mailslot 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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