CVE-2026-91847

Bookly <= 28.1 - Unauthenticated Insecure Direct Object Reference

2026-09-17 00:00

Strategic Overview

Status: Patched in 28.2
Affected Plugin: Online Scheduling and Appointment Booking System – Bookly
Affected Version: <= 28.1
CVSS: 5.3Medium
Weakness type: CWE-639 · Authorization Bypass Through User-Controlled Key
CVE: CVE-2026-91847

View all Online Scheduling and Appointment Booking System – Bookly vulnerabilities

At a glance

CVE-2026-91847 is a medium-severity Authorization Bypass Through User-Controlled Key vulnerability in the Online Scheduling and Appointment Booking System WordPress plugin, affecting versions <= 28.1. It carries a CVSS score of 5.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 28.2; sites on affected versions should update now. Disclosed September 2026, reported by vuxvinh.

Vulnerability Overview

The Bookly plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 28.1. This is due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to perform an unauthorized action.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user.

CWE-639: Authorization Bypass Through User-Controlled Key

Reaching this weakness in Online Scheduling and Appointment Booking System <= 28.1 takes no account at all. Authorization bypass through a user-controlled key, often called insecure direct object reference, means the application looks up a record by an identifier from the request without checking that the caller owns it.

Changing a number in the request is enough to read or modify other users' records, which on commerce and membership sites means customer data. For Online Scheduling and Appointment Booking System the fix is 28.2: builds <= 28.1 are affected, anything from 28.2 onward is not.

Remediation

Update to version 28.2, or a newer patched version

How does WordSec protect against this?

This one needs no account at all, which puts it outside what login hardening can reach; WordSec's login security narrows the account-level paths around it, and the firewall is what inspects the request itself. None of that substitutes for the fix: Online Scheduling and Appointment Booking System 28.2 closes this, and updating the plugin is the step that ends it.

Login Security
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-91847 https://www.wordfence.com/threat-intel/vulnerabilities/id/9220d87a-6016-4d24-9d47-81db5a6609a0 https://nvd.nist.gov/vuln/detail/CVE-2026-91847

Related records

Same weakness class

Other vulnerabilities in Online Scheduling and Appointment Booking System – Bookly

CVSS Vector

5.3

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityNone

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