A critical privilege escalation vulnerability in Craft CMS allows unauthenticated attackers to gain administrative access by exploiting flawed registration logic, posing a severe risk to site integrity.

This vulnerability is caused by improper privilege management where the system fails to validate the admin flag during user registration. An unauthenticated attacker can register an account using the email address of a deactivated administrator to inherit their elevated privileges when public registration is enabled and email verification is disabled.

The exploitation of this vulnerability results in a full compromise of the administrative interface, granting attackers the ability to modify content, alter system settings, and potentially execute arbitrary code depending on the environment configuration. Given the CVSS score of 9.8, this flaw represents a critical threat to business operations, data confidentiality, and system integrity. Unauthorized administrative access can lead to significant reputational damage and the complete takeover of the affected web application.

Immediate Action: Update Craft CMS to version 5.10.11 or later immediately to resolve the privilege inheritance flaw.

Proactive Monitoring: Review user registration logs for suspicious activity or unexpected account creation events that correlate with existing administrative email addresses.

Compensating Controls: Disable public user registration and ensure email verification is enabled as a mandatory security best practice until the update can be applied.

Public Exploit Available: No (exploit_available: false)

This vulnerability presents an extreme risk due to the ease with which an attacker can escalate privileges without requiring prior authentication. Organizations utilizing Craft CMS must prioritize updating to version 5.10.11 immediately. Failure to address this issue leaves the application vulnerable to complete unauthorized administrative takeover.