---
id: "CVE-2026-112971"
page: "https://infrastack.ai/live/CVE-2026-112971"
kind: "vulnerability"
aliases: ["CVE-2026-112971"]
title: "Windows 11 26H1 SMB Client: heap overflow lets a local user gain higher privileges"
severity: "high"
cvss: 7.0
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "Windows 11 version 26H1", "fixed": ["10.0.28000.3501"], "affected": ">= 10.0.28000.0, < 10.0.28000.3501", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["infrastructure", "local-privilege-escalation", "smb", "windows", "windows-11"]
not_affected_if: ["no-local-users", "patched"]
published_at: "2026-11-10T19:18:47+00:00"
first_seen_at: "2026-11-10T19:24:35+00:00"
updated_at: "2026-11-11T00:02:55+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-112971", "first_seen_at": "2026-11-10T19:24:35+00:00"}, {"source": "analyst", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-112971", "first_seen_at": "2026-11-11T00:02:55+00:00", "cites": ["https://nvd.nist.gov/vuln/detail/CVE-2026-112971"]}]
exploit_sources: []
---

# Windows 11 26H1 SMB Client: heap overflow lets a local user gain higher privileges

Link for people: https://infrastack.ai/live/CVE-2026-112971 (this .md is for agents)

Microsoft's CVE record describes a heap-based buffer overflow (CWE-122) in the Windows SMB Client. An authorized local attacker can use it to elevate privileges. CVSS 7.0 (AV:L/AC:H/PR:L). Microsoft's CNA data lists only Windows 11 version 26H1 as affected, with builds before 10.0.28000.3501 vulnerable. No exploitation or public proof of concept found.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Windows 11 version 26H1 affected >= 10.0.28000.0, < 10.0.28000.3501 fixed 10.0.28000.3501

## How to check

On Windows 11 26H1, run 'winver' or PowerShell '[System.Environment]::OSVersion.Version'. If the build is below 10.0.28000.3501 you are exposed. Other Windows versions are not listed as affected in Microsoft's CVE record; confirm on the MSRC page.

## Fix

Install the November 2026 Patch Tuesday cumulative update for Windows 11 26H1 (build 10.0.28000.3501 or later). The KB number is unconfirmed.

## Timeline

- 2026-11-10T19:24:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-112971
- 2026-11-11T00:02:55+00:00 analyst https://nvd.nist.gov/vuln/detail/CVE-2026-112971 — NVD carries Microsoft CNA data: only Windows 11 26H1 listed, affected 10.0.28000.0 <10.0.28000.3501. MSRC page is JS-only, unreadable, so nothing verified. No exploitation or PoC found; not in KEV.

## Documents

- [describes] NVD CVE-2026-112971 (Microsoft CNA data) https://nvd.nist.gov/vuln/detail/CVE-2026-112971

## From the sources

Heap-based buffer overflow in Windows SMB Client allows an authorized attacker to elevate privileges locally.

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