Windows Push Notifications: Heap-based buffer overflow leads to privilege escalation
Summary
A heap-based buffer overflow in the Windows Push Notifications component allows an authorized local user to elevate privileges. Successful exploitation can give the attacker full control of the affected system, including confidentiality, integrity and availability. The attacker needs a local low-privilege account and local access, so the flaw is mainly a second-stage risk after an initial compromise.
Affected
- Windows 10 Version 1607 (10.0.14393.0 before 10.0.14393.9612)
- Windows 10 Version 1809 (10.0.17763.0 before 10.0.17763.9376)
- Windows 10 Version 21H2 (10.0.19044.0 before 10.0.19044.7807)
- Windows 10 Version 22H2 (10.0.19045.0 before 10.0.19045.7807)
- Windows 11 Version 23H2 (10.0.22631.0 before 10.0.22631.7652)
- Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9711)
- Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9711)
- Windows 11 Version 26H1 (10.0.28000.0 before 10.0.28000.3231)
- Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9711)
- Windows Server 2016 incl. Server Core (10.0.14393.0 before 10.0.14393.9612)
- Windows Server 2019 incl. Server Core (10.0.17763.0 before 10.0.17763.9376)
- Windows Server 2022 (10.0.20348.0 before 10.0.20348.5761)
- Windows Server 2025 (10.0.26100.0 before 10.0.26100.33650)
Fixed in
- Fixed by Microsoft's October 13, 2026 security updates, per the build numbers listed above.
- KB article numbers: Unknown. Retrieve them from the MSRC advisory before deployment.
Workaround
Unknown. No vendor-listed workaround was found in the retrieved sources. Check the 'Mitigations' and 'Workarounds' sections of the MSRC advisory.
Exploitation
- No evidence of exploitation in the wild found.
- Microsoft rates exploit code maturity as Unproven (E:U).
- No public proof of concept found.
- No CISA KEV listing found; not directly verified.
- SonicWall lists a detection signature for this CVE. This is not evidence of attacks, but it suggests that exploit-like code exists or is being tested.
- EPSS about 0.37% (Vulners).
Our recommendation
- Install the October 2026 Windows security updates on all listed systems, prioritizing multi-user systems such as RDS hosts, shared PCs and file servers.
- Verify the support status of Windows 10 Version 1607 on Microsoft's lifecycle page. If it is out of support, replace these systems or move them to a supported build.
- Until patched, restrict local logon to trusted users, remove unneeded local administrator rights and monitor for unexpected privilege changes.
- Check the MSRC advisory for mitigations and KB numbers.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Push Notifications
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation more likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5126651, KB5126655, KB5126657, KB5126646, KB5127648, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-83867 msrc.microsoft.com
- Vulners NVD mirror: CVE-2026-83867 vulners.com
- Vulners Rapid7 record (EPSS): CVE-2026-83867 vulners.com
- SonicWall October 2026 Microsoft bulletin coverage www.sonicwall.com
- Strix.ai: CVE-2026-83867 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 2 Nov 2026, 02:45.
Original description (NVD)
Heap-based buffer overflow in Windows Push Notifications allows an authorized attacker to elevate privileges 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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