CVE-2026-39861
published 2026-04-21CVE-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…
PriorityP265critical10CVSS 3.1
AVNACLPRNUINSCCHIHAH
EPSS
0.52%
40.1th percentile
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.
Affected
3 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| anthropic-ai | claude-code | >= 0 < 2.1.64 | 2.1.64 |
| anthropic | claude_code | < 2.1.64 | 2.1.64 |
| anthropics | claude-code | < 2.1.64 | 2.1.64 |
CVSS provenance
nvdv3.110.0CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
nvdv4.07.7HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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GHSA
Claude Code: Sandbox Escape via Symlink Following Allows Arbitrary File Write Outside Workspace
ghsa·2026-04-21
CVE-2026-39861 [HIGH] CWE-22 Claude Code: Sandbox Escape via Symlink Following Allows Arbitrary File Write Outside Workspace
Claude Code: Sandbox Escape via Symlink Following Allows Arbitrary File Write Outside Workspace
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
VulDB
Anthropic claude-code up to 2.1.63 Symlink path traversal (GHSA-vp62-r36r-9xqp / EUVD-2026-24033)
vuldb·2026-04-21·CVSS 7.7
CVE-2026-39861 [HIGH] Anthropic claude-code up to 2.1.63 Symlink path traversal (GHSA-vp62-r36r-9xqp / EUVD-2026-24033)
A vulnerability described as critical has been identified in Anthropic claude-code up to 2.1.63. The impacted element is an unknown function of the component Symlink Handler. The manipulation results in path traversal.
This vulnerability was named CVE-2026-39861. The attack may be performed from remote. There is no available exploit.
Upgrading the affected component is recommended.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-04-21
Published