Microsoft Windows: Information disclosure in ActiveSyncProvider
Summary
Several Windows 10 and Windows 11 builds contain an out-of-bounds read in ActiveSyncProvider. An unauthenticated attacker on the network can read memory contents, but only if a user interacts with the attack (UI:R). The CVE record describes a confidentiality impact only, and does not describe writes or code execution.
Affected
- Windows 10 Version 1607: 10.0.14393.0 to before 10.0.14393.9688
- Windows 10 Version 1809: 10.0.17763.0 to before 10.0.17763.9487
- Windows 10 Version 21H2: 10.0.19044.0 to before 10.0.19044.7846
- Windows 10 Version 22H2: 10.0.19045.0 to before 10.0.19045.7846
- Windows 11 Version 23H2: 10.0.22631.0 to before 10.0.22631.7711
- Windows 11 Version 24H2: 10.0.26100.0 to before 10.0.26100.9974
- Windows 11 Version 25H2: 10.0.26200.0 to before 10.0.26200.9974
- Windows 11 Version 26H1: 10.0.28000.0 to before 10.0.28000.3501
- Windows 11 Version 26H2: 10.0.26300.0 to before 10.0.26300.9974
Fixed in
- Install the November 2026 cumulative update for your build (fixed builds as listed above).
- KB numbers: Unknown.
Workaround
Unknown.
Exploitation
- Not exploited in the wild according to SANS ISC.
- Rapid7 rates exploitation as unlikely and reports no public disclosure.
- No public proof of concept found.
Our recommendation
- Install the November 2026 cumulative update on all affected Windows devices, prioritising out-of-support Windows 10 versions and systems that handle mobile sync.
- Check the MSRC Security Update Guide for the authoritative product list and KB numbers before deployment.
- Check whether any Windows device exposes or uses ActiveSync-related services, especially if it is reachable from outside the network.
- Review the MSRC Mitigations section for any interim measures.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – ActiveSyncProvider
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation unlikely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5131291, KB5131085, KB5131096, KB5131087, KB5132061, KB5132043
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide: CVE-2026-119889 msrc.microsoft.com
- CVE.org record: CVE-2026-119889 www.cve.org
- SANS ISC Patch Tuesday diary isc.sans.edu
- Rapid7 Patch Tuesday November 2026 www.rapid7.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, 12:07.
Original description (NVD)
Out-of-bounds read in ActiveSyncProvider allows an unauthorized attacker to disclose information over a network.
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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