GHSA-q5hj-mxqh-vv77: Claude Code: Trust Dialog Bypass via Git Worktree Spoofing Allows Arbitrary Code Execution

Claude Code had a security flaw where it checked a git worktree (a Git feature allowing multiple branch checkouts in separate directories) `commondir` file to decide if a folder was trustworthy, but didn't verify the file's contents. An attacker could create a malicious repository with a fake `commondir` file pointing to a folder the victim had previously trusted, tricking Claude Code into skipping its safety dialog and running malicious code from `.claude/settings.json` (a configuration file). This attack required the victim to clone the malicious repository and open it in Claude Code, and the attacker had to know a path the victim had already marked as safe.