Git checkout ambiguous refname warning on 40-hex SHA (Plugin4Shell)

Ibrahim Saud@tektrix

•updated Sep 18, 2026•0•0•0

Detects instances where AI coding agents (such as Claude Code, Copilot, etc.) execute git commands (checkout, fetch, clone) using a branch name or reference formatted as a 40-character hex string. This behavior is indicative of a 'Plugin4Shell' style bypass, where an attacker crafts a branch name that mimics a commit SHA to cause ambiguous refname errors or hijack repository operations.