Detect Google Skia Out-of-Bounds Write (CVE-2026-3909) in Elastic Security
Detects exploitation attempts targeting CVE-2026-3909, an out-of-bounds write vulnerability in Google Skia graphics library. Skia is embedded in Chrome and other Google products. Exploitation can lead to arbitrary code execution via crafted web content or malicious files. This vulnerability is confirmed exploited in the wild (CISA KEV).
MITRE ATT&CK
- Tactic
- Initial Access Execution
Elastic Detection Query
sequence by host.name with maxspan=2m
[process where event.type == "start"
and process.parent.name in ("chrome.exe", "msedge.exe", "brave.exe", "opera.exe")
and process.name in ("cmd.exe", "powershell.exe", "wscript.exe", "cscript.exe", "mshta.exe", "rundll32.exe", "regsvr32.exe")]
[any where event.category in ("network", "process")
and (network.direction == "outbound" or process.name : "*")]EQL sequence rule correlating a browser spawning a shell interpreter with subsequent network or process activity within a 2-minute window, indicative of Skia exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Browser-based enterprise deployment tools launching installers
- Automated CI pipelines running from browser context on developer machines
- Browser extension helper processes with legitimate network activity
Other platforms for CVE-2026-3909
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 Browser Spawning Shell (Windows)
Expected signal: Sysmon Event ID 1 showing cmd.exe with ParentImage containing chrome.exe; Windows Security 4688 process creation log
- Test 2Simulate Suspicious Outbound Network Connection from Browser Process (Linux)
Expected signal: Auditd or Sysmon-for-Linux network connection event showing process named 'chrome' connecting to port 4444
- Test 3Simulate Renderer Sandbox Escape via LOLBin Execution (Windows)
Expected signal: Sysmon Event ID 1 with regsvr32.exe CommandLine containing /i:http and scrobj.dll; Sysmon Event ID 3 network connection from regsvr32.exe
- Test 4Skia OOB Write Crash Reproduction (macOS — Lab Only)
Expected signal: Chrome crash report generated in crash-dumps-dir; macOS Console logs show SIGSEGV or SIGABRT from renderer process
Unlock Pro Content
Get the full detection package for CVE-2026-3909 including response playbook, investigation guide, and atomic red team tests.