Executive brief
The Classified Listing - Mobile Number Verification plugin for WordPress fails to validate OTP codes on the server side, allowing attackers to bypass authentication and log in as any user. An attacker who knows or guesses a target user's phone number can take over their account—including administrator accounts—by submitting a fake OTP through the plugin's Firebase login flow.
Technical details
The vulnerability is an authentication bypass in the process_otp_login() function due to missing server-side validation of OTP codes submitted via the Firebase OTP login flow. An unauthenticated attacker can submit an arbitrary OTP and UID to authenticate as any registered user, provided they know the target's phone number and OTP login is enabled with Firebase as the verification gateway. Successful exploitation leads to full account takeover, including administrator accounts if an admin has registered a phone number. Exploitation requires knowledge of the victim's phone number but does not require prior authentication or interaction from the victim. A patch is available in version 1.7.0 or later.
Affected products
- RadiusTheme Classified Listing - Mobile Number Verification up to and including 1.6.0
Timeline
- 2026-08-26: disclosed
- 2026-08-04: other: Fixed in version 1.7.0