CVE-2026-104898: Online Scheduling and Appointment Booking System missing authorization check vulnerability
medium 6.8 published 2026-10-10 · updated 2026-10-13
- Affected versions
- 28.4 and older
- Fixed in
- 28.5 *
- Latest version
- 28.7
- Severity
- Medium · CVSS 6.8
- Active installs
- 60,000+
- Type
- Missing authorization check
* The source does not name a fixed version; this is the first wordpress.org release after the last affected version.
What an attacker needs
- Access: A logged-in account with Subscriber-level access or higher.
CVSS vector (score by Wordfence): CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
What to do now
- Update Online Scheduling and Appointment Booking System to 28.5 or newer (the latest is 28.7): Dashboard → Updates, or Plugins → “update now”.
- If you cannot update right away, deactivate it until you can.
- Turn on auto-updates for it: Plugins → “Enable auto-updates” on its row.
- Not sure which version you run? Check your version against every known Online Scheduling and Appointment Booking System issue.
With WP-CLI:
wp plugin get bookly-responsive-appointment-booking-tool --field=version. - If you ran an affected version and something looks off (new admin users, spam pages, redirects), run the free scan below.
The advisory
The Online Scheduling and Appointment Booking System – Bookly plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 28.4 via the 'id, wp_user_id' parameter due to missing validation on a user controlled key. This makes it possible for authenticated attackers, with subscriber-level access and above, to overwrite the WordPress account binding of any Bookly staff record, including those owned by administrators, effectively hijacking a higher-privileged staff member's account association and escalating privileges. Exploitation requires the attacking user to be linked to at least one Bookly staff record, which occurs by default whenever an admin enables the bookly_gen_allow_staff_edit_profile option (active on fresh installs) and links a WordPress user to a staff entry.
References
- NVD CVE-2026-104898 nvd.nist.gov
- Wordfence advisory www.wordfence.com
- Code change (fix) plugins.trac.wordpress.org
- Plugin source plugins.trac.wordpress.org
Related
Ran an affected version? Check your site for signs of a hack
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Where this data comes from
- CVE record, score and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
- Versions and install counts: wordpress.org/plugins/bookly-responsive-appointment-booking-tool (Plugins API), fetched 2026-11-04.
- The summary, “what an attacker needs” and “what to do” sections are our plain-English reading of the record and the plugin's release history; the quoted description is the record's own text. Spot an error? Email Daniel.