Microsoft Windows: Information disclosure in Program Compatibility Assistant
Summary
A local information disclosure flaw (CWE-908, uninitialized resource) exists in the Windows Program Compatibility Assistant Service on multiple Windows 10, Windows 11 and Windows Server versions. An authorized local user with low privileges can read sensitive information, with no user interaction required. The impact is limited to confidentiality; integrity and availability are not affected. Risk is highest on shared multi-user hosts such as terminal servers.
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, including Server Core (builds before 10.0.14393.9688)
- Windows Server 2019, including Server Core (builds before 10.0.17763.9487)
- Windows Server 2022 (builds before 10.0.20348.5870)
Fixed in
Fixed in the Microsoft security update of November 2026 (Patch Tuesday). The fixed builds correspond to the upper limits of the affected ranges listed above. KB numbers: unknown; verify in the MSRC Security Update Guide before deployment.
Workaround
Unknown. No workaround is documented in the sources reviewed. Installing the security update is the recommended fix.
Exploitation
- Not known to be exploited in the wild.
- CISA SSVC: Exploitation none, Automatable no, Technical Impact partial.
- Public proof of concept: none known; this has not been verified against exploit repositories.
- Rapid7 rates it 'Exploitation Less Likely'.
Our recommendation
- Install the November 2026 cumulative update on all affected Windows 10, Windows 11 and Windows Server systems.
- Prioritise multi-user hosts such as terminal servers, RDS systems and kiosks.
- Patch CVE-2026-123388 (elevation of privilege in the same service, fixed in the same release) at the same time.
- Confirm build numbers and KB IDs in the MSRC guide before rollout.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – Windows Program Compatibility Assistant Service
- 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
- CVE.org record CVE-2026-88247 www.cve.org
- Microsoft Security Update Guide CVE-2026-88247 msrc.microsoft.com
- Rapid7 Patch Tuesday November 2026 www.rapid7.com
- BleepingComputer Patch Tuesday November 2026 www.bleepingcomputer.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, 16:36.
Original description (NVD)
Use of uninitialized resource in Windows Program Compatibility Assistant Service 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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