Executive brief
The Grav Login plugin handles user account registration. An attacker can determine which email addresses are registered on a site by repeatedly attempting to register with different email addresses and observing the system responses, since the registration form discloses whether an email is already in use. Without rate limiting on this endpoint, attackers can efficiently enumerate valid email addresses for targeting or social engineering attacks.
Technical details
This is an information disclosure vulnerability (CWE-203/CWE-204) in the register() method of classes/Login.php. When a user submits a registration request, the code explicitly throws a distinct RuntimeException (EMAIL_NOT_AVAILABLE) if the email address already belongs to an existing account, but allows registration to proceed silently for new emails. An attacker can exploit this by sending repeated registration requests with different email addresses over the network; each response reveals whether that address is registered. The registration endpoint lacks rate limiting that would be present on login and password-reset endpoints. The patch in version 3.9.1 returns identical generic messages regardless of whether the submitted email is already registered.
Affected products
- Grav Login plugin before 3.9.1
Timeline
- 2026-08-25: disclosed
- 2026-08-25: patched: Version 3.9.1 released
- 2026-08-10: advisory: GitHub Security Advisory GHSA-crh8-xm27-j9g9