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.
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History
Tue, 21 Apr 2026 02:45:00 +0000
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Anthropics
Anthropics claude Code |
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Anthropics
Anthropics claude Code |
Tue, 21 Apr 2026 01:15:00 +0000
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| 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. | |
| Title | Claude Code: Sandbox Escape via Symlink Following Allows Arbitrary File Write Outside Workspace | |
| Weaknesses | CWE-22 CWE-61 |
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cvssV4_0
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-04-21T00:56:39.062Z
Updated: 2026-04-21T00:56:39.062Z
Reserved: 2026-04-07T19:13:20.379Z
Link: CVE-2026-39861
No data.
Status : Received
Published: 2026-04-21T01:16:06.647
Modified: 2026-04-21T01:16:06.647
Link: CVE-2026-39861
No data.