Ghost is an open source blogging platform that's used in more than 52,600 live websites, most of them located in the U.S., the U.K., German, China, France, Canada, and India.
Tracked as CVE-2022-41654 (CVSS score: 9.6), the authentication bypass vulnerability allows unprivileged users (i.e., members) to make unauthorized modifications to newsletter settings.
Cisco Talos, which discovered the shortcoming, said it could enable a member to change the system-wide default newsletter that all users are subscribed to by default.
"This gives unprivileged users the ability to view and change settings they were not intended to have access to," Ghost noted in an advisory published on November 28, 2022. "They are not able to escalate their privileges permanently or get access to further information."
The CMS platform blamed the bug due to a "gap" in its API validation, adding it found no evidence that the issue has been exploited in the wild.
Also patched by Ghost is an enumeration vulnerability in the login functionality (CVE-2022-41697, CVSS score: 5.3) that could lead to the disclosure of sensitive information.
Per Talos, this flaw could be leveraged by an attacker to enumerate all valid users of Ghost by supplying an email address, which could then be used to narrow down potential targets for a next-stage phishing attack.
The flaws have been addressed in the Ghost (Pro) managed hosting service, but users who self-host the service and run a version between 4.46.0 and 4.48.7 or any version of v5 up to and including 5.22.6 are required to update to versions 4.48.8 and 5.22.7.
(The story has been updated with a revised CVSS score for CVE-2022-41654 based on an advisory issued by Cisco Talos.)