The vulnerability exists in Parse Server’s /verificationEmailRequest endpoint. Key detail from the official description: the endpoint returns distinct error codes depending on whether an email address belongs to a registered user, is already verified, or does not exist. This inconsistency enables an attacker to determine which email addresses are registered in the application (user‑enumeration), classified as CWE‑204. The impact is a disclosure of valid user accounts, which can be leveraged for phishing or credential‑reuse attacks; it does not allow code execution or direct access to other data, but it compromises user confidentiality.

Deployments of Parse Server using any version prior to 8.6.34 or 9.6.0‑alpha.8 with email verification enabled (verifyUserEmails: true) are affected. The vulnerability is present in all releases listed before the fix, as noted in the vendor’s release announcements.

Based on the description, the likely attack vector is remote HTTP requests to the publicly exposed /verificationEmailRequest endpoint; no authentication is required. The CVSS score of 6.3 indicates medium severity, and the EPSS score of less than 1% suggests a low probability of active exploitation. The vulnerability is not listed in CISA’s KEV catalog. Exploitation requires only the ability to send standard HTTP requests and observe response codes, making it accessible to attackers with minimal effort, though the low EPSS mitigates immediate concern.