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Vulnerabilities

Vulnerability · CVE-2026-39861

Claude Code is an agentic coding tool.

Published Apr 21, 2026 · catalog updated Jun 17, 2026 · claude code

Check if you run it

No confirmed exploitation is on record for CVE-2026-39861. EPSS is 0.80%. Act only if a listed version of claude code is installed.

Severity
High7.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.80%
Remediation
Advisory link
Affected products
cpe anthropic/claude code

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe anthropic/claude codeversion unspecified

How to fix CVE-2026-39861

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-39861. EPSS is 0.80%. Act only if a listed version of claude code is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-22: Path Traversal; CWE-61. EPSS 0.80%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 21, 2026 · NIST NVD

    Detected

    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 confirmati

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 confirmati

Sources

  • CVE.orgVulnerability recordCVE-2026-39861

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-39861

    30-day exploitation probability 0.8%

    first.org
  • NIST NVDVulnerability recordCVE-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 proce

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.