{
 "license": "CC-BY-4.0",
 "attribution": "Fide AI, Agentic Cyber Explorer",
 "url": "https://agentic-cyber-explorer.pages.dev/events/anthropic-claude-code-sandboxing-2025/",
 "asOf": "2026-09-26",
 "id": "anthropic-claude-code-sandboxing-2025",
 "date": "2025-10-20",
 "datePrecision": "day",
 "title": "Anthropic adds OS-level filesystem and network sandboxing to Claude Code and open-sources the runtime",
 "lane": "defense",
 "kind": "tool-release",
 "summary": "Anthropic describes sandboxing for Claude Code that restricts file writes to permitted directories and routes network traffic through a proxy that only allows approved hosts, so a prompt-injected agent cannot modify sensitive files or exfiltrate data freely. Anthropic says internal use showed an 84% reduction in permission prompts, and it released the sandbox runtime, built on bubblewrap and macOS seatbelt, as an open-source research preview.",
 "whyItMatters": "It is a concrete containment control that limits the blast radius of prompt injection in coding agents regardless of model behavior.",
 "actors": [
  "anthropic"
 ],
 "topics": [
  "sandbox-containment",
  "prompt-injection",
  "data-exfiltration"
 ],
 "atlas": [
  "sandbox",
  "credentials",
  "human-approver"
 ],
 "artifacts": [],
 "sources": [
  {
   "url": "https://www.anthropic.com/engineering/claude-code-sandboxing",
   "publisher": "Anthropic",
   "title": "Beyond permission prompts: making Claude Code more secure and autonomous",
   "date": "2025-10-20",
   "type": "primary",
   "accessed": "2026-09-25"
  }
 ],
 "keyFacts": [
  {
   "fact": "Anthropic reports sandboxing safely reduced permission prompts by 84% in internal usage.",
   "locator": "Main post"
  },
  {
   "fact": "Runtime released as anthropic-experimental/sandbox-runtime, using Linux bubblewrap and macOS seatbelt.",
   "locator": "Open source section"
  }
 ],
 "significance": 3,
 "fideQuestions": [
  "FID-076"
 ],
 "methods": [
  "agent-data-exfiltration",
  "human-approval",
  "sandboxing-egress"
 ],
 "review": "assistant-drafted",
 "addedOn": "2026-09-25"
}