Windows Client for NFS: Local privilege escalation via integer overflow
Summary
An integer overflow or wraparound in the Windows Client for NFS component of Microsoft Windows allows an authorized local attacker to elevate privileges. An attacker who already has a user account on the system can gain higher privileges, with high impact on confidentiality, integrity and availability. The flaw is not remotely exploitable, and exposure depends on whether the Windows Client for NFS feature is installed.
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 2012 incl. Server Core (6.2.9200.0 before 6.2.9200.26434)
- Windows Server 2012 R2 incl. Server Core (6.3.9600.0 before 6.3.9600.23470)
- Windows Server 2016 (10.0.14393.0 before 10.0.14393.9612)
Fixed in
- Install the October 2026 security update for each affected product (published 13 October 2026).
- The fixed build is the upper bound of each range above. The Microsoft advisory could not be retrieved, so verify the builds on the MSRC page before rollout.
- Patch names seen in scanner listings, not verified: KB5126646 (Windows Server 2025), KB5126651 (Windows 10 1809 / Server 2019).
Workaround
- No official Microsoft workaround confirmed. Unknown.
- A secondary source suggests disabling the Windows NFS client feature where it is not needed, or restricting who can start NFS operations. Not verified against MSRC.
Exploitation
- No evidence of exploitation in the wild found.
- No public proof of concept found.
- CISA SSVC data: exploitation none, automatable no, technical impact total.
- EPSS about 0.003, indicating a low predicted exploitation probability.
Our recommendation
- Apply the October 2026 security update to all affected systems, starting with shared workstations, terminal servers and hosts with many user logons.
- Check whether the Windows Client for NFS feature is installed and used, and disable it where it is not needed.
- Verify the fixed builds on the MSRC advisory and check the support status of Windows 10 1607 and 1809; plan upgrades for unsupported systems.
- Monitor CISA KEV and vendor channels for exploitation reports, and review local logons and administrative rights.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Client for NFS
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5126657, KB5126835, KB5126836, KB5126868, KB5126651, KB5126655
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide (CVE-2026-70113) msrc.microsoft.com
- NVD data via Vulners vulners.com
- CNA record via Vulners cvelist vulners.com
- OpenCVE CVE-2026-70113 app.opencve.io
- Strix AI CVE summary www.strix.ai
- Patch Tuesday coverage October 2026 (SonicWall) 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, 04:12.
Original description (NVD)
Integer overflow or wraparound in Windows Client for NFS 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.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.