Digits: WordPress Mobile Number Signup and Login <= 9.1.0.5 - Authenticated (Subscriber+) Privilege Escalation via 'digits_reg_userrole' Parameter

The Digits: WordPress Mobile Number Signup and Login plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 9.1.0.5. This is due to missing authorization and role validation in the `dig_update_wpwc_custom_fields()` function. This makes it possible for authenticated attackers, with Subscriber-level access and above, to escalate their privileges to Administrator by submitting a forged `digits_reg_userrole` value during profile update, granted the site administrator has configured the built-in DIGITS User Role field.