---
id: "CVE-2026-83563"
page: "https://infrastack.ai/live/CVE-2026-83563"
kind: "vulnerability"
aliases: ["CVE-2026-83563"]
title: "Windows Winlogon: heap overflow lets a local user gain higher privileges"
severity: "high"
cvss: 7.8
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "local", "privilege-escalation", "windows", "winlogon"]
not_affected_if: ["no-local-accounts"]
published_at: "2026-11-10T19:21:23+00:00"
first_seen_at: "2026-11-10T19:25:17+00:00"
updated_at: "2026-11-10T21:12:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-83563", "first_seen_at": "2026-11-10T19:25:17+00:00"}, {"source": "analyst", "url": "https://advisories.checkpoint.com/defense/advisories/public/2026/cpai-2026-17533.html/", "first_seen_at": "2026-11-10T21:12:50+00:00", "cites": ["https://advisories.checkpoint.com/defense/advisories/public/2026/cpai-2026-17533.html/"]}]
exploit_sources: []
---

# Windows Winlogon: heap overflow lets a local user gain higher privileges

Link for people: https://infrastack.ai/live/CVE-2026-83563 (this .md is for agents)

A heap-based buffer overflow in Windows Winlogon, the logon component, lets an authorized local user elevate their privileges. The sources do not give affected versions, fixed builds, or a patch reference.

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

## How to check

Unknown: Microsoft's KB and build numbers are not yet confirmed. Check whether hosts run Windows 11 23H2/24H2/25H2/26H1/26H2 or Server 2025 (winver), and compare the build with the fixed build in the MSRC update guide entry for CVE-2026-83563.

## Fix

Install the November 2026 Windows cumulative update. KB and build numbers are not yet confirmed from Microsoft.

## Timeline

- 2026-11-10T19:25:17+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-83563
- 2026-11-10T21:12:50+00:00 analyst https://advisories.checkpoint.com/defense/advisories/public/2026/cpai-2026-17533.html/ — MSRC update guide and NVD pages did not render via web-cli; no primary Microsoft page read, so nothing verified. Check Point CPAI-2026-17533 (secondary, citing Microsoft) lists affected Windows 11 23H2/24H2/25H2/26H1/26H2 (x64, ARM64) and Server 2025 (incl. Server Core). KB numbers and fixed builds still unknown; settle via MSRC update guide entry.

## Documents

- [mentions] CPAI-2026-17533 Check Point: Microsoft Winlogon EoP (CVE-2026-83563) https://advisories.checkpoint.com/defense/advisories/public/2026/cpai-2026-17533.html/

## From the sources

Heap-based buffer overflow in Winlogon allows an authorized attacker to elevate privileges locally.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_