Microsoft Windows: Out-of-bounds read in Windows Event Logging Service
Summary
An out-of-bounds read in the Windows Event Logging Service allows an unauthorized attacker to execute code over a network, according to the CVE record. Several Windows 11 branches and Windows Server 2022 and 2025 are affected. The NVD vector rates attack complexity as high and requires no privileges, but the sources disagree on whether user interaction is needed. No public proof of concept or known exploitation was found in the sources reviewed.
Affected
- Windows 11 23H2: 10.0.22631.0 to before 10.0.22631.7652
- Windows 11 24H2: 10.0.26100.0 to before 10.0.26100.9711
- Windows 11 25H2: 10.0.26200.0 to before 10.0.26200.9711
- Windows 11 26H1: 10.0.28000.0 to before 10.0.28000.3231
- Windows 11 26H2: 10.0.26300.0 to before 10.0.26300.9711
- Windows Server 2022: 10.0.20348.0 to before 10.0.20348.5761
- Windows Server 2025 (incl. Server Core): 10.0.26100.0 to before 10.0.26100.33650
Fixed in
Fixed builds as reported by aggregators, not yet confirmed on the MSRC page:
- Windows 11 23H2: 10.0.22631.7652 (KB5126653, October 2026)
- Windows 11 24H2, 25H2, 26H2: 10.0.26100.9711 / 10.0.26200.9711 / 10.0.26300.9711
- Windows 11 26H1: 10.0.28000.3231
- Windows Server 2022: 10.0.20348.5761
- Windows Server 2025 (incl. Server Core): 10.0.26100.33650 (KB5126646, October 2026)
Workaround
Unknown.
- No vendor-documented workaround found; install the security update.
Exploitation
- CISA KEV: not listed in the sources reviewed; recheck the catalog.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- No public proof of concept found.
- EPSS about 0.006.
Our recommendation
- Install the October 2026 cumulative update on all affected systems, starting with Windows Server and internet-facing or remotely reachable hosts.
- Verify build and KB numbers on the MSRC advisory before rollout.
- Check whether the Event Logging Service is reachable from untrusted networks.
- Recheck the CISA KEV catalog and public PoC sources weekly.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide: CVE-2026-83856 msrc.microsoft.com
- VulnERS: NVD record CVE-2026-83856 vulners.com
- Strix: CVE-2026-83856 www.strix.ai
- Tenable Nessus plugin 365473 www.tenable.com
- OpenCVE: CVE-2026-83856 app.opencve.io
- VulDB: vulnerability 419053 vuldb.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 1 Nov 2026, 19:25.
Original description (NVD)
Out-of-bounds read in Windows Event Logging Service allows an unauthorized attacker to execute code 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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