---
id: "CVE-2026-68820"
kind: "vulnerability"
aliases: ["CVE-2026-68820"]
title: "Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges\u2026"
severity: "high"
cvss: 7.0
epss: null
exploited: true
status: "open"
category: "other"
products: [{"name": "Microsoft Windows Ancillary Function Driver for WinSock", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "Windows Ancillary Function Driver for WinSock (afd.sys)", "fixed": ["26100.9168", "26200.9168", "28000.2704", "22631.7517", "19044.7663", "19045.7663", "17763.9121", "14393.9418", "20348.5499", "6.3.9600.23338", "6.2.9200.26280"], "affected": "Windows builds below fixed build: 26100 < 26100.9168; 26200 < 26200.9168; 28000 < 28000.2704; 22631 < 22631.7517; 19044/19045 < 19044.7663/19045.7663; 17763 < 17763.9121; 14393 < 14393.9418; 20348 < 20348.5499; 6.3.9600 < 6.3.9600.23338; 6.2.9200 < 6.2.9200.26280", "ecosystem": "vendor"}, {"name": "microsoft windows 10 1607", "fixed": ["10.0.14393.9418"], "affected": "< 10.0.14393.9418", "ecosystem": "vendor"}, {"name": "microsoft windows 10 1809", "fixed": ["10.0.17763.9115"], "affected": "< 10.0.17763.9115", "ecosystem": "vendor"}, {"name": "microsoft windows 10 21h2", "fixed": ["10.0.19044.7663"], "affected": "< 10.0.19044.7663", "ecosystem": "vendor"}, {"name": "microsoft windows 10 22h2", "fixed": ["10.0.19045.7663"], "affected": "< 10.0.19045.7663", "ecosystem": "vendor"}, {"name": "microsoft windows 11 23h2", "fixed": ["10.0.22631.7517"], "affected": "< 10.0.22631.7517", "ecosystem": "vendor"}, {"name": "microsoft windows 11 24h2", "fixed": ["10.0.26100.9106"], "affected": "< 10.0.26100.9106", "ecosystem": "vendor"}, {"name": "microsoft windows 11 25h2", "fixed": ["10.0.26200.9106"], "affected": "< 10.0.26200.9106", "ecosystem": "vendor"}, {"name": "microsoft windows 11 26h1", "fixed": ["10.0.28000.2704"], "affected": "< 10.0.28000.2704", "ecosystem": "vendor"}, {"name": "microsoft windows server 2012", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft windows server 2012", "fixed": [], "affected": "= r2", "ecosystem": "vendor"}, {"name": "microsoft windows server 2016", "fixed": ["10.0.14393.9418"], "affected": "< 10.0.14393.9418", "ecosystem": "vendor"}, {"name": "microsoft windows server 2019", "fixed": ["10.0.17763.9115"], "affected": "< 10.0.17763.9115", "ecosystem": "vendor"}, {"name": "microsoft windows server 2022", "fixed": ["10.0.20348.5440"], "affected": "< 10.0.20348.5440", "ecosystem": "vendor"}, {"name": "microsoft windows server 2025", "fixed": ["10.0.26100.33222"], "affected": "< 10.0.26100.33222", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "lazarus", "local-privilege-escalation", "microsoft-windows", "other", "self-hosted", "windows"]
not_affected_if: ["non-windows", "patched-aug-2026"]
published_at: "2026-08-11T00:00:00+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T23:44:51+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-68820", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T21:41:23+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68820", "first_seen_at": "2026-10-23T23:44:51+00:00"}]
---

# Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges…

Use-after-free (race) in afd.sys lets a local low-privilege user reach SYSTEM. Microsoft marks it Exploitation Detected. KernelSight reports Lazarus used it as a zero-day (Operation Dream Job, deploying FudModule v3.1) for about five weeks before the 11 Aug 2026 patch. It needs a foothold first and cannot be reached remotely. No public PoC.

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

## Affected

- vendor:Microsoft Windows Ancillary Function Driver for WinSock affected ? fixed ?
- vendor:Windows Ancillary Function Driver for WinSock (afd.sys) affected Windows builds below fixed build: 26100 < 26100.9168; 26200 < 26200.9168; 28000 < 28000.2704; 22631 < 22631.7517; 19044/19045 < 19044.7663/19045.7663; 17763 < 17763.9121; 14393 < 14393.9418; 20348 < 20348.5499; 6.3.9600 < 6.3.9600.23338; 6.2.9200 < 6.2.9200.26280 fixed 26100.9168, 26200.9168, 28000.2704, 22631.7517, 19044.7663, 19045.7663, 17763.9121, 14393.9418, 20348.5499, 6.3.9600.23338, 6.2.9200.26280
- vendor:microsoft windows 10 1607 affected < 10.0.14393.9418 fixed 10.0.14393.9418
- vendor:microsoft windows 10 1809 affected < 10.0.17763.9115 fixed 10.0.17763.9115
- vendor:microsoft windows 10 21h2 affected < 10.0.19044.7663 fixed 10.0.19044.7663
- vendor:microsoft windows 10 22h2 affected < 10.0.19045.7663 fixed 10.0.19045.7663
- vendor:microsoft windows 11 23h2 affected < 10.0.22631.7517 fixed 10.0.22631.7517
- vendor:microsoft windows 11 24h2 affected < 10.0.26100.9106 fixed 10.0.26100.9106
- vendor:microsoft windows 11 25h2 affected < 10.0.26200.9106 fixed 10.0.26200.9106
- vendor:microsoft windows 11 26h1 affected < 10.0.28000.2704 fixed 10.0.28000.2704
- vendor:microsoft windows server 2012 affected ? fixed ?
- vendor:microsoft windows server 2012 affected = r2 fixed ?
- vendor:microsoft windows server 2016 affected < 10.0.14393.9418 fixed 10.0.14393.9418
- vendor:microsoft windows server 2019 affected < 10.0.17763.9115 fixed 10.0.17763.9115
- vendor:microsoft windows server 2022 affected < 10.0.20348.5440 fixed 10.0.20348.5440
- vendor:microsoft windows server 2025 affected < 10.0.26100.33222 fixed 10.0.26100.33222

## How to check

Check the OS build with winver or [System.Environment]::OSVersion. Any build below the fixed build for your branch is exposed (e.g. 26100 < 26100.9168, 26200 < 26200.9168, 22631 < 22631.7517, 19045 < 19045.7663, 17763 < 17763.9121). Reboot after patching, because the old driver stays loaded until then. Inventory by build number, not by update status. Detection (KernelSight): bulk ETW provider loss, security-product kernel callbacks disappearing, NT Kernel Logger stopping.

## Fix

Install the August 2026 (or later) cumulative update. Windows 11 24H2/25H2: KB5121003 (26100.9168 / 26200.9168). Other fixed builds: 10.0.28000.2704, 10.0.22631.7517, 10.0.19044.7663 and 10.0.19045.7663, 10.0.17763.9121, 10.0.14393.9418, 10.0.20348.5499, 6.3.9600.23338, 6.2.9200.26280. Then reboot.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-68820
- 2026-10-23T21:41:23+00:00 analyst — MSRC advisory (released 2026-08-11) plus CVE.org build list: exploited zero-day, no public PoC. KernelSight reports Lazarus use and KB5121003 for 24H2/25H2; I didn't check that against Microsoft's KB or Check Point. CVE.org lists some builds twice, so the per-SKU mapping is approximate.
- 2026-10-23T23:44:51+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-68820

## Documents

- [advisory] MSRC: Windows Ancillary Function Driver for WinSock EoP (CVE-2026-68820) https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-68820
- [describes] KernelSight: CVE-2026-68820 case study https://splintersfury.github.io/KernelSight/case-studies/CVE-2026-68820/
- [fix] CVE record CVE-2026-68820 (CNA Microsoft) fixed builds https://www.cve.org/CVERecord?id=CVE-2026-68820

## From the sources

Microsoft Windows Ancillary Function Driver for WinSock contains a use-after-free vulnerability that allows an authorized attacker to elevate privileges locally.

CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_