CVE-2026-39861 (GCVE-0-2026-39861)

Vulnerability from cvelistv5 – Published: 2026-04-21 00:56 – Updated: 2026-04-21 13:44
VLAI
Title
Claude Code: Sandbox Escape via Symlink Following Allows Arbitrary File Write Outside Workspace
Summary
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.
Severity
7.7 (High)
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
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-04-21 13:44 UTC
CWE
  • CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
  • CWE-61 - UNIX Symbolic Link (Symlink) Following
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 8007 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
anthropics claude-code Affected: < 2.1.64
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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