Detect Microsoft Windows Type Confusion Vulnerability (CVE-2026-21519) in Splunk
Detects exploitation of CVE-2026-21519, a type confusion vulnerability (CWE-843) in Microsoft Windows. Type confusion vulnerabilities occur when code allocates or initializes a resource using one type but accesses it using an incompatible type, leading to out-of-bounds memory access, arbitrary code execution, or privilege escalation. This CVE is listed on the CISA Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.
MITRE ATT&CK
SPL Detection Query
index=windows (source="WinEventLog:Security" OR source="WinEventLog:System" OR source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational")
| eval event_id=coalesce(EventCode, event_id)
| eval process_name=coalesce(Process_Name, process_name, Image)
| eval parent_process=coalesce(Parent_Process_Name, ParentImage)
| eval cmdline=coalesce(Process_Command_Line, CommandLine)
| eval service_file=coalesce(Service_File_Name, ImagePath)
| where (
(event_id=4688 AND (match(cmdline, "SeDebugPrivilege|SeImpersonatePrivilege|SeAssignPrimaryTokenPrivilege")))
OR (event_id=7045 AND match(service_file, "(?i)(\\AppData\\|\\Temp\\|\.tmp)"))
OR (event_id=4697 AND match(service_file, "(?i)(\\AppData\\|\\Temp\\|\.tmp)"))
OR (event_id=6 AND NOT match(parent_process, "(?i)(MsMpEng\.exe|services\.exe|wininit\.exe|TrustedInstaller\.exe)"))
OR (event_id=1 AND match(parent_process, "(?i)(lsass\.exe|winlogon\.exe|csrss\.exe)") AND NOT match(process_name, "(?i)(conhost\.exe|werfault\.exe|WerFaultSecure\.exe)"))
)
| eval risk_score=case(
event_id=6 AND NOT match(parent_process, "(?i)(MsMpEng\.exe|services\.exe)"), 90,
event_id=1 AND match(parent_process, "(?i)(lsass\.exe|winlogon\.exe)"), 85,
event_id IN (7045,4697) AND match(service_file, "(?i)(\\AppData\\|\\Temp\\)"), 80,
true(), 60
)
| table _time, host, user, process_name, parent_process, cmdline, service_file, event_id, risk_score
| sort - risk_score _timeSplunk detection for Windows type confusion exploitation indicators including privilege manipulation, suspicious service installs, driver loads from non-system initiators, and anomalous child processes from protected system processes.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Third-party endpoint security products performing legitimate kernel operations
- IT administrators deploying software via service installation in non-standard paths
- Developer workstations running debugging tools that request elevated privileges
- Automated patch management tools writing temporary files before service installation
Other platforms for CVE-2026-21519
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Simulate Anomalous Child Process from Winlogon
Expected signal: Sysmon EventID 1 showing cmd.exe or similar process with an unexpected parent, Windows Security EventID 4688 capturing the new process creation with command line arguments.
- Test 2Privilege Token Enumeration via Command Line
Expected signal: Windows Security EventID 4688 with CommandLine containing privilege-related arguments, Sysmon EventID 1 capturing the full process creation with integrity level.
- Test 3Suspicious Service Installation from Temp Directory
Expected signal: Windows System EventID 7045 (new service installed) with ServiceImagePath pointing to %TEMP%, Sysmon EventID 13 capturing registry writes for the new service key under HKLM\SYSTEM\CurrentControlSet\Services.
- Test 4Unsigned Driver Load Simulation via Sysmon
Expected signal: Sysmon EventID 6 (DriverLoad) with the ImageLoaded path pointing to a non-standard location and the initiating process being a user-mode application rather than services.exe or wininit.exe.
Unlock Pro Content
Get the full detection package for CVE-2026-21519 including response playbook, investigation guide, and atomic red team tests.