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Vulnerability record · CVE-2026-13424 · published 16 August 2026

CVE-2026-13424: Cross-site scripting vulnerability

The Online Scheduling and Appointment Booking System – Bookly plugin for WordPress is vulnerable to Stored Cross-Site Scripting via bookly_speed_up_update_addons AJAX action in all versions up to, and including, 27.7 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The injection point is the bookly_speed_up_update_addons AJAX action, which is registered as wp_ajax_nopriv_* and therefore reachable without authentication; the payload is stored verbatim in the bookly_log.details column when a request is submitted without a valid signature, and executes when an administrator later views the Diagnostics → Logs page.

7.2 CVSS 3.1 High EPSS 0.58% · top 54.5% CWE-79 · Cross-site scripting Deferred
7.2CVSS 3.1 base score
0.58%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
10References
20 Aug 2026Last modified by NVD

Description

The Online Scheduling and Appointment Booking System – Bookly plugin for WordPress is vulnerable to Stored Cross-Site Scripting via bookly_speed_up_update_addons AJAX action in all versions up to, and including, 27.7 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The injection point is the bookly_speed_up_update_addons AJAX action, which is registered as wp_ajax_nopriv_* and therefore reachable without authentication; the payload is stored verbatim in the bookly_log.details column when a request is submitted without a valid signature, and executes when an administrator later views the Diagnostics → Logs page.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

References

LinkTags
https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/27.5/backend/modules/diagnost
https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/27.5/backend/modules/diagnost
https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/27.5/lib/PluginsUpdater.php#L
https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/27.5/lib/PluginsUpdater.php#L
https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/27.7/backend/modules/diagnost
https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/27.7/backend/modules/diagnost
https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/27.7/lib/PluginsUpdater.php#L
https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/27.7/lib/PluginsUpdater.php#L
https://plugins.trac.wordpress.org/changeset?reponame=&old=3637918%40bookly-responsive-appointment-booking-tool&new=3637
https://www.wordfence.com/threat-intel/vulnerabilities/id/cfb53e44-7f9d-490f-b938-f428c20219d7?source=cve

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Source: NIST National Vulnerability Database (record CVE-2026-13424), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.