Auth bypass in Themetechmount Truebooker – Appointment Booking And Scheduler System

CVE-2026-18315

The TrueBooker – Appointment Booking and Scheduler System plugin for WordPress is vulnerable to Authorization Bypass Through User-Controlled Key leading to Account Takeover in all versions up to, and including, 1.2.6. This is due to the admin_user_create_cus AJAX handler lacking any authentication or capability check before passing the attacker-supplied truebooker_wp_user_id parameter directly to wp_update_user. This makes it possible for unauthenticated attackers to overwrite the email address of any WordPress user — including an administrator — and then complete the standard WordPress lost-password flow to fully take over the targeted account.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.006 (46.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 46.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-18315: held from 0.006 to 0.006.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2026-18315?
CVE-2026-18315 is a critical-severity vulnerability in Themetechmount Truebooker – Appointment Booking And Scheduler System, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 9.8/10. Published 2026-08-19.
How severe is CVE-2026-18315?
Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2026-18315 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.