Crash with STATUS_STACK_BUFFER_OVERRUN (0xC0000409) during Chrome MCP browser automation

Description

Claude Code process crashed with exit code 3221226505 (0xC0000409 = STATUS_STACK_BUFFER_OVERRUN) during Chrome MCP browser automation on Windows.

STATUS_STACK_BUFFER_OVERRUN indicates that Windows /GS (Buffer Security Check) detected stack buffer corruption and terminated the process. This is a security-mitigation-triggered crash, not a random segfault.

Environment

• OS: Windows 11 Home 10.0.26200
• Claude Code: 2.1.170 (embedded in Claude Desktop)
• Claude Desktop: 1.11847.5.0 (Microsoft Store)
• Model in use: Opus 4.6

Steps to reproduce

1. Start a Claude Code session inside Claude Desktop on Windows
2. Use Chrome MCP (mcp__Claude_in_Chrome__*) tools to interact with a web page (in this case, OSF profile settings at osf.io)
3. Perform a sequence of browser automation actions:

• Fill multiple form fields (social link inputs — LinkedIn, X, GitHub)
• Scroll down the page
• Click the Save button

1. During or immediately after the Save button click, Claude Code crashes

Error

The crash dialog shows:

Claude Code process exited with code 3221226505

3221226505 (decimal) = 0xC0000409 (hex) = STATUS_STACK_BUFFER_OVERRUN

This is Windows' /GS compiler security check detecting stack buffer corruption and forcing process termination.

Notes

• The crash occurred mid-conversation during active Chrome MCP tool execution
• The session was otherwise operating normally before the crash
• Not yet confirmed whether this is reliably reproducible (single occurrence so far)
• The exit code is specific enough to narrow the crash location to a stack-cookie-protected function boundary in the native code path (likely in the Chrome extension ↔ native messaging ↔ Electron boundary)