Windows SMB Client: Use after free allows local privilege escalation
Summary
A use-after-free vulnerability (CWE-416) in the Windows SMB client allows a local attacker to elevate privileges. The attacker needs a low-privilege account on the affected machine and the attack is highly complex, so it is not remotely exploitable. The impact on the local system is total (confidentiality, integrity and availability), so it is most relevant as a second stage after phishing or a stolen credential.
Affected
- Microsoft Windows 11 version 26H1 (x64 and ARM64): 10.0.28000.0 before 10.0.28000.3501
- Older Windows versions (for example 23H2, 24H2, 25H2 or Windows 10) are not listed in the sources reviewed. Confirm against the MSRC product table before ruling them out.
Fixed in
- Windows 11 version 26H1: build 10.0.28000.3501 or later, included in the November 2026 security update
- KB number: Unknown. Check the MSRC advisory or Windows Update.
Workaround
Unknown. No vendor workaround was found. The security update is the only confirmed fix.
Exploitation
- No public proof-of-concept exploit found. The MSRC CVSS vector carries E:U (exploit code maturity Unproven).
- In the wild: Unconfirmed. Talos lists four CVEs including this one as the November exploited vulnerability, without saying which one was exploited.
- CISA SSVC: Exploitation none, not automatable. Not listed in the CISA KEV catalog according to a secondary source; verify directly.
Our recommendation
- Run an asset inventory to find Windows 11 26H1 systems.
- Install the November 2026 security update on affected systems as part of the normal monthly patch cycle.
- Prioritise shared workstations and servers with local user logons.
- Check the MSRC product table for other Windows versions and monitor the CISA KEV catalog for changes.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows SMB Client
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation more likely
- Product family
- Windows
- Updates (KB)
- KB5132059
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide: CVE-2026-112970 msrc.microsoft.com
- CVE.org record CVE-2026-112970 www.cve.org
- Talos Patch Tuesday summary, November 2026 blog.talosintelligence.com
- Qualys Patch Tuesday review, November 2026 blog.qualys.com
- Strix summary CVE-2026-112970 (secondary) 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 11 Nov 2026, 09:10.
Original description (NVD)
Use after free in Windows SMB Client 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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