Microsoft OpenSSH for Windows: Use-after-free allows local privilege escalation
Summary
Microsoft OpenSSH for Windows contains a use-after-free weakness (CWE-416) that allows an authorized local user to elevate privileges. The attack requires local access and a low-privileged account; there is no network attack vector. Risk is highest on multi-user servers and jump hosts where OpenSSH for Windows is enabled.
Affected
- Windows 10 Version 1809 and Windows Server 2019 (builds before 10.0.17763.9376, per the CVE record)
- Other listed Windows 10, Windows 11 and Windows Server 2022/2025 builds (see CVE record)
- Note: the CPE lists Windows 10 1809, but the research notes could not confirm the full affected-product table. Confirm on MSRC.
Fixed in
- Unknown. The CVE record gives the upper build bound for Windows 10 1809 / Server 2019 as 10.0.17763.9376; confirm the fixed build on MSRC.
- Install the latest cumulative update for your OS.
Workaround
- If SSH is not required, stop and disable the OpenSSH server service.
- No other workaround is confirmed by the sources.
Exploitation
- CISA SSVC: exploitation none, automatable no, technical impact total.
- Not listed in the CISA KEV catalog.
- EPSS about 0.004.
- No public proof of concept found; treat status as unknown until checked.
Our recommendation
- Install the October 2026 cumulative update for your OS and confirm the fix on MSRC.
- Check whether OpenSSH for Windows is installed and enabled; disable it if it is not needed.
- Limit local logons on servers and jump hosts, and monitor for unexpected privilege changes.
- Make sure tickets reference CVE-2026-83769 and not the similar CVE-2026-97816.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – OpenSSH for Windows
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation more likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5127648, KB5126651, KB5126655, KB5126657, KB5126646, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-83769 msrc.microsoft.com
- OpenCVE: CVE-2026-83769 app.opencve.io
- Vulners NVD record: CVE-2026-83769 vulners.com
- Vulners Rapid7 record: CVE-2026-83769 (EPSS) vulners.com
- Microsoft Support: KB5134124 Windows 10 1809 update support.microsoft.com
- Qualys: Microsoft Patch Tuesday October 2026 review blog.qualys.com
- SonicWall: Microsoft security bulletin coverage October 2026 www.sonicwall.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 2 Nov 2026, 03:04.
Original description (NVD)
Use after free in OpenSSH for Windows 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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