AI Threat Alert
Claude Code is an agentic coding tool. Prior to version 2.1.64, Claude Code's sandbox did not prevent sandboxed processes from creating symlinks pointing to locations outside the workspace. When Claude Code subsequently wrote to a path within such a symlink, its unsandboxed process followed the...
Full CISO analysis pending enrichment.
Affected Systems
| Package | Ecosystem | Vulnerable Range | Patched |
|---|---|---|---|
| @anthropic-ai/claude-code | npm | < 2.1.64 | 2.1.64 |
Do you use @anthropic-ai/claude-code? You're affected.
Severity & Risk
Recommended Action
Patch available
Update @anthropic-ai/claude-code to version 2.1.64
Compliance Impact
Compliance analysis pending. Sign in for full compliance mapping when available.
Frequently Asked Questions
What is CVE-2026-39861?
Claude Code is an agentic coding tool. Prior to version 2.1.64, Claude Code's sandbox did not prevent sandboxed processes from creating symlinks pointing to locations outside the workspace. When Claude Code subsequently wrote to a path within such a symlink, its unsandboxed process followed the symlink and wrote to the target location outside the workspace without prompting the user for confirmation. This allowed a sandbox escape where neither the sandboxed command nor the unsandboxed app could
Is CVE-2026-39861 actively exploited?
No confirmed active exploitation of CVE-2026-39861 has been reported, but organizations should still patch proactively.
How to fix CVE-2026-39861?
Update to patched version: @anthropic-ai/claude-code 2.1.64.
What is the CVSS score for CVE-2026-39861?
No CVSS score has been assigned yet.
Technical Details
NVD Description
Claude Code is an agentic coding tool. Prior to version 2.1.64, Claude Code's sandbox did not prevent sandboxed processes from creating symlinks pointing to locations outside the workspace. When Claude Code subsequently wrote to a path within such a symlink, its unsandboxed process followed the symlink and wrote to the target location outside the workspace without prompting the user for confirmation. This allowed a sandbox escape where neither the sandboxed command nor the unsandboxed app could independently write outside the workspace, but their combination could write to arbitrary locations, potentially leading to code execution outside the sandbox. Reliably exploiting this required the ability to add untrusted content into a Claude Code context window to trigger sandboxed code execution via prompt injection. Users on standard Claude Code auto-update have received this fix automatically. Users performing manual updates are advised to update to version 2.1.64 or later.