Ghost CMS Staff Invite Token Exposure Leads to Privilege Escalation

Executive Summary

This vulnerability affects Ghost, a Node.js content management system. Between versions 4.39.0 and 6.64.0, staff users with permission to view staff invites could access the secret tokens of pending invites, including those for higher-privilege roles. This allowed them to escalate their own privileges by accepting these invites.

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Detection Guidance

To detect this vulnerability, check Ghost CMS versions between 4.39.0 and 6.64.0. Verify if staff users can access invite tokens via API endpoints. Review logs for unauthorized invite acceptance or privilege escalation attempts.

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Impact Analysis

An attacker with staff access could exploit this to gain higher privileges, potentially taking control of the Ghost instance. This could lead to unauthorized access, data breaches, or system compromise. The attack requires low privileges and no user interaction, making it easier to exploit.

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Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection requirements or HIPAA's security rules. A breach may result in legal penalties, reputational damage, and loss of trust due to compromised confidentiality and integrity of user data.

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Mitigation Strategies

Update Ghost to version 6.64.0 or later to patch the vulnerability. For self-hosted instances, use Docker or Ghost-CLI to upgrade. Remove any pending staff invites with higher privileges to prevent unauthorized access.

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