Windows AppContainer: Information disclosure through weak authentication
Summary
A weakness in the authentication mechanism of Windows AppContainer, the sandbox boundary for restricted app processes, allows information disclosure. An attacker needs an existing local account or code running on the host, and the CVSS base score is 6.5 (medium). Confidentiality is highly affected, while integrity and availability are not. Microsoft's CVE record and CISA SSVC show no known exploitation.
Affected
- Windows 10 Version 1607 (10.0.14393.0 before 10.0.14393.9688)
- Windows 10 Version 1809 (10.0.17763.0 before 10.0.17763.9487)
- Windows 10 Version 21H2 (10.0.19044.0 before 10.0.19044.7846)
- Windows 10 Version 22H2 (10.0.19045.0 before 10.0.19045.7846)
- Windows 11 Version 23H2 (10.0.22631.0 before 10.0.22631.7711)
- Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9974)
- Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9974)
- Windows 11 Version 26H1 (10.0.28000.0 before 10.0.28000.3501)
- Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9974)
- Windows Server 2016 incl. Server Core (10.0.14393.0 before 10.0.14393.9688)
- Windows Server 2019 incl. Server Core (10.0.17763.0 before 10.0.17763.9487)
- Windows Server 2022 (10.0.20348.0 before 10.0.20348.5870)
Fixed in
- Security update of November 2026 for the affected Windows versions, with the builds listed under affected.
- Build numbers for Windows 10 21H2, 22H2, Windows 11 23H2 and Windows Server 2016 to 2022 are taken from third-party aggregators and are not yet confirmed by Microsoft.
- KB numbers reported by third parties: KB5131090 (Windows Server 2022) and KB5131096 (Windows 10 21H2). Unverified.
- Unknown: whether Windows Server 2025, LTSC variants and other editions are covered by the same fix.
Workaround
None known. The fix is delivered as a security update.
Exploitation
- CISA SSVC: exploitation none, not automatable, partial technical impact.
- Rapid7 rates exploitation as less likely and reports no public disclosure.
- Not reported as exploited in the wild.
- No public proof of concept found.
- The CVSS temporal values are E:U (unproven) and RC:C (confirmed).
Our recommendation
- Install the November 2026 Windows security update on all affected systems and verify the build number against the Microsoft Security Update Guide.
- Prioritise multi-user terminal servers, shared workstations and hosts that run untrusted or third-party code.
- Restrict local accounts and limit who can run code on servers and workstations.
- Monitor for unusual local activity until patching is complete.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – Windows AppContainer
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5132061, KB5132043, KB5131085, KB5131090, KB5131096, KB5131080
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-96018 msrc.microsoft.com
- CVE.org record CVE-2026-96018 www.cve.org
- Rapid7: Patch Tuesday November 2026 www.rapid7.com
- Senserva: KB5131090 senserva.com
- Senserva: KB5131096 senserva.com
- Strix: CVE-2026-96018 (third-party aggregation) 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, 11:56.
Original description (NVD)
Weak authentication in Windows AppContainer 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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