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LSASS Crash Via Netlogon Stack Buffer Overflow - CVE-2026-41089
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LSASS Crash Via Netlogon Stack Buffer Overflow - CVE-2026-41089
Using Splunk · Default · pySigma 2.0.1
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title: LSASS Crash Via Netlogon Stack Buffer Overflow - CVE-2026-41089
id: f8a66a02-4a16-46e5-b7fd-a42c8a93d137
status: experimental
description: |
Detects a crash of the LSASS process where netlogon.dll is the faulting module and the exception code is STATUS_STACK_BUFFER_OVERRUN (0xc0000409).
This crash, especially on Domain Controllers, might indicate the exploitation of CVE-2026-41089, a denial of service (DoS) vulnerability,
which exists in the Netlogon component of Windows and can be triggered by sending specially crafted requests to the Netlogon service,
leading to a stack-based buffer overflow and subsequent crash of the LSASS process.
references:
- https://aretiq.ai/research/vul260513-cve-2026-41089-microsoft-windows-netlogon-buildsamlogonresponse-stack-based-buffer-overflow-rce/
- https://learn.microsoft.com/en-us/shows/inside/c0000409
- https://github.com/p3Nt3st3r-sTAr/CVE-2026-41089
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-41089
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2026-06-02
tags:
- attack.impact
- attack.t1499
- cve.2026-41089
- detection.emerging-threats
logsource:
product: windows
service: application
detection:
selection:
Provider_Name: 'Application Error'
EventID: 1000
AppName: 'lsass.exe'
ModuleName: 'netlogon.dll'
ExceptionCode: 'c0000409' # STATUS_STACK_BUFFER_OVERRUN
condition: selection
falsepositives:
- Unknown
level: high
CLI command
Sigma CLI 4.0.0 · Install matching versions, then run from the Phoenix project directory.
python -m pip install 'sigma-cli==4.0.0' 'pysigma==2.0.1' 'pysigma-backend-splunk==3.0.0'
sigma convert --without-pipeline -t splunk -f default 'sigma/rules-emerging-threats/2026/Exploits/CVE-2026-41089/win_application_error_exploit_cve_2026_41089_lsass_netlogon_crash.yml'