Pheditor, a single-file PHP-based file editor and manager, contains a hardcoded default password 'admin' (stored as a SHA-512 hash) in versions 2.0.1 through 2.0.5. There is no mechanism to enforce a password change upon first login, leaving deployments using default credentials fully exposed. An attacker exploiting this weakness gains unrestricted access to file editing, file upload, and terminal features. This effectively enables arbitrary file read/write operations and remote code execution on the affected server. The vulnerability is particularly dangerous because it requires no exploitation sophistication beyond using a known default credential. The issue affects any deployment that has not manually changed the default password. A patch has been released in version 2.0.6 which addresses this hardcoded credential issue.