CVE-2026-40068: anthropic claude_code Improper Input Validation

Vulnerability summary

CVE-2026-40068 is a high (CVSS 8.8) Improper Input Validation vulnerability in anthropic claude_code. EPSS estimates a 0.56% chance of exploitation in the next 30 days, higher than 45.9% of scored vulnerabilities.

Timeline

1. 05-05-2026
   PublishedVulnerability first disclosed.
2. 06-05-2026
   Last modifiedVulnerability information updated.

Description

In versions 2.1.63 through 2.1.83 of Claude Code, the folder trust determination logic used the git worktree commondir file without validating its contents. An attacker could craft a malicious repository with a commondir file pointing to a path the victim had previously trusted, causing Claude Code to bypass its trust confirmation dialog and immediately execute hooks defined in `.claude/settings.json`. Exploitation requires the victim to clone the malicious repository and run Claude Code within it, and the attacker must know or guess a path the victim had already trusted. This issue has been fixed in version 2.1.84.

• CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
• CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.