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Claude CodeApplication · Anthropic

CVE-2026-25725

CRITICAL · 10.0 CVSS v3.1 Published 2026-02-06
Fix available
A fix is available. Upgrade to 2.1.2 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Claude Code is an agentic coding tool. Prior to version 2.1.2, Claude Code's bubblewrap sandboxing mechanism failed to properly protect the .claude/settings.json configuration file when it did not exist at startup. While the parent directory was mounted as writable and .claude/settings.local.json was explicitly protected with read-only constraints, settings.json was not protected if it was missing. This allowed malicious code running inside the sandbox to create this file and inject persistent hooks (such as SessionStart commands) that would execute with host privileges when Claude Code was restarted. This issue has been patched in version 2.1.2.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Claude Code versions before 2.1.2, the bubblewrap sandboxing mechanism mounted the .claude parent directory as writable when settings.json did not exist at startup, but failed to apply read-only protection to settings.json itself (unlike settings.local.json). This allowed malicious code executing inside the sandbox to create settings.json and inject persistent hooks such as SessionStart commands that execute with host privileges upon restart.

MitigationUpgrade to Claude Code version 2.1.2 or later, which patches the bubblewrap sandbox to properly protect settings.json even when the file does not exist at startup.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Claude CodeApplication
Affected:< 2.1.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Claude Code version
    Run 'claude --version' or check the application's version information to determine if it is before 2.1.2
    Affected if Version is less than 2.1.2
  2. Locate the .claude settings directory
    Find the .claude directory in the user's home directory (typically ~/.claude/)
    Affected if The .claude directory exists and is accessible
  3. Check for presence of settings.json
    Examine whether settings.json file exists in the .claude directory
    Affected if settings.json exists in the .claude directory (especially if it was created after installing an affected version)
  4. Inspect settings.json for suspicious SessionStart commands
    Open and review settings.json for any SessionStart, onRestart, or similar persistent hook configurations that could execute with host privileges
    Affected if settings.json contains SessionStart commands or other persistent hooks that were not intentionally configured by the user

You are affected if Claude Code version is below 2.1.2 AND settings.json exists in the .claude directory with any SessionStart or persistent hook configurations that you did not intentionally create.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.1.2 or later
Fixed in 2.1.2
Interim mitigation

Upgrade to Claude Code version 2.1.2 or later, which patches the bubblewrap sandbox to properly protect settings.json even when the file does not exist at startup.

Recommended fix High confidence

Claude Code 2.1.2

  1. Check current Claude Code version by running 'claude --version' or checking the application
  2. Download Claude Code version 2.1.2 from the official GitHub releases page (github.com)
  3. Install the updated version following the standard installation process for your platform
  4. Restart Claude Code to ensure the patched version is running
  5. Verify the version is now 2.1.2 using 'claude --version'

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Claude Code Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-25725 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data