CVE-2026-8840
Booking calendar, Appointment Booking System <= 3.2.36 - Missing Authorization to Unauthenticated Arbitrary Modification via wpdevart_payment AJAX Action
Description
The Booking calendar, Appointment Booking System plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 3.2.36. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for unauthenticated attackers to mark arbitrary reservations as paid or completed, cancel legitimate payments, auto-approve reservations, and trigger transactional booking emails by writing attacker-supplied payment status and transaction data directly into the payments table. The auto-approval of reservations is only triggered when the 'enable_psuccess_approval' site option is enabled, but payment status manipulation and email dispatch are exploitable regardless of that setting.
INFO
Published Date :
Aug. 15, 2026, 3:16 a.m.
Last Modified :
Aug. 15, 2026, 3:16 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-8840
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update the Booking calendar plugin to the latest version.
- Verify plugin settings related to payment approval.
- Monitor the payments table for unauthorized entries.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-8840.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-8840 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-8840
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-8840 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-8840 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Aug. 15, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'wpdevart', 'product': 'Booking calendar, Appointment Booking System', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '3.2.36'}], 'defaultStatus': 'unaffected'}] Added Description The Booking calendar, Appointment Booking System plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 3.2.36. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for unauthenticated attackers to mark arbitrary reservations as paid or completed, cancel legitimate payments, auto-approve reservations, and trigger transactional booking emails by writing attacker-supplied payment status and transaction data directly into the payments table. The auto-approval of reservations is only triggered when the 'enable_psuccess_approval' site option is enabled, but payment status manipulation and email dispatch are exploitable regardless of that setting. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Added CWE CWE-862 Added Reference https://plugins.trac.wordpress.org/browser/booking-calendar/tags/3.2.35/admin/controllers/Payment.php#L16 Added Reference https://plugins.trac.wordpress.org/browser/booking-calendar/tags/3.2.35/admin/controllers/Payment.php#L26 Added Reference https://plugins.trac.wordpress.org/browser/booking-calendar/tags/3.2.35/booking_calendar.php#L131 Added Reference https://plugins.trac.wordpress.org/browser/booking-calendar/tags/3.2.35/booking_calendar.php#L578 Added Reference https://plugins.trac.wordpress.org/browser/booking-calendar/tags/3.2.36/admin/controllers/Payment.php#L16 Added Reference https://plugins.trac.wordpress.org/browser/booking-calendar/tags/3.2.36/admin/controllers/Payment.php#L26 Added Reference https://plugins.trac.wordpress.org/browser/booking-calendar/tags/3.2.36/booking_calendar.php#L131 Added Reference https://plugins.trac.wordpress.org/browser/booking-calendar/tags/3.2.36/booking_calendar.php#L578 Added Reference https://www.wordfence.com/threat-intel/vulnerabilities/id/88409bb0-5cb0-4f63-b8f0-d72f54fa17b0?source=cve