Impact

Improper authentication on some endpoints used for member actions would allow an attacker to perform member-only actions, and read member information.

Vulnerable versions

This security vulnerability is present in Ghost v4.46.0-v5.89.5.

Ghost(Pro) customers are automatically updated to fixed versions ahead of disclosure.

If you're a self-hoster, please follow our update instructions.

Patches

v5.89.5 contains a fix for this issue.

Workarounds

Disable site membership in Ghost settings.

For more information

If you have any questions or comments about this advisory:

Email us at security@ghost.org

An authentication bypass vulnerability exists in the newsletter subscription functionality of Ghost Foundation Ghost 5.9.4. A specially-crafted HTTP request can lead to increased privileges. An attacker can send an HTTP request to trigger this vulnerability.