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

Type Values Removed Values Added
First Time appeared Anthropics
Anthropics claude Code
Vendors & Products Anthropics
Anthropics claude Code

Tue, 21 Apr 2026 01:15:00 +0000

Type Values Removed Values Added
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
References
Metrics cvssV4_0

{'score': 7.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-04-21T00:56:39.062Z

Reserved: 2026-04-07T19:13:20.379Z

Link: CVE-2026-39861

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-04-21T01:16:06.647

Modified: 2026-04-21T01:16:06.647

Link: CVE-2026-39861

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-21T02:30:25Z

Weaknesses