BaseFortify

Publication date: 2025-11-19

Last updated on: 2025-11-25

Assigner: GitHub, Inc.

Description

Claude Code is an agentic coding tool. Prior to version 1.0.39, when running on a machine with Yarn 3.0 or above, Claude Code could have been tricked to execute code contained in a project via yarn plugins before the user accepted the startup trust dialog. Exploiting this would have required a user to start Claude Code in an untrusted directory and to be using Yarn 3.0 or above. This issue has been patched in version 1.0.39.

CVSS Scores

EPSS Scores

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Meta Information

Published

2025-11-19

Last Modified

2025-11-25

Generated

2026-07-06

AI Q&A

2025-11-19

EPSS Evaluated

2026-07-05

NVD

CVE-2025-65099

Affected Vendors & Products

Vendor	Product	Version / Range
anthropic	claude_code	to 1.0.39 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-94	The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

Attack-Flow Graph

Executive Summary

This vulnerability in Claude Code versions prior to 1.0.39 occurs when running on a machine with Yarn 3.0 or above. Claude Code could be tricked into executing code contained in a project via yarn plugins before the user accepted the startup trust dialog. Exploiting this requires the user to start Claude Code in an untrusted directory while using Yarn 3.0 or above. The issue has been fixed in version 1.0.39.

Impact Analysis

If exploited, this vulnerability could lead to the execution of untrusted code on your machine without your explicit consent, potentially compromising your system's security and integrity. This could result in unauthorized actions or data exposure before you have a chance to approve the startup trust dialog.

Mitigation Strategies

To mitigate this vulnerability, update Claude Code to version 1.0.39 or later. Additionally, avoid running Claude Code in untrusted directories when using Yarn 3.0 or above until the update is applied.

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