CVE-2026-2519

Online Scheduling and Appointment Booking System – Bookly <= 27.0 - Unauthenticated Price Manipulation via 'tips'

2026-04-08 00:00

Strategic Overview

Status: Patched in 27.1
Affected Plugin: Online Scheduling and Appointment Booking System – Bookly
Affected Version: <= 27.0
CVSS: 5.3Medium
Weakness type: CWE-472 · External Control of Assumed-Immutable Web Parameter
CVE: CVE-2026-2519

View all Online Scheduling and Appointment Booking System – Bookly vulnerabilities

At a glance

CVE-2026-2519 is a medium-severity External Control of Assumed-Immutable Web Parameter vulnerability in the Online Scheduling and Appointment Booking System WordPress plugin, affecting versions <= 27.0. 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 27.1; sites on affected versions should update now. Disclosed April 2026, reported by Youssef Elouaer.

Vulnerability Overview

The Online Scheduling and Appointment Booking System – Bookly plugin for WordPress is vulnerable to price manipulation via the 'tips' parameter in all versions up to, and including, 27.0. This is due to the plugin trusting a user-supplied input without server-side validation against the configured price. This makes it possible for unauthenticated attackers to submit a negative number to the 'tips' parameter, causing the total price to be reduced to zero.

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-472: External Control of Assumed-Immutable Web Parameter

Online Scheduling and Appointment Booking System <= 27.0 carries this weakness at tips, and reaching it takes no account at all. External control of an assumed-immutable parameter means the code trusts a value it believes cannot be changed by the caller, when in fact the request carries it.

Editing that field changes the outcome of the operation, which on commerce plugins means altered prices or totals and on account flows means acting as another user. For Online Scheduling and Appointment Booking System the fix is 27.1: builds <= 27.0 are affected, anything from 27.1 onward is not.

Remediation

Update to version 27.1, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Online Scheduling and Appointment Booking System 27.1 closes this, and updating the plugin is the step that ends it.

Firewall
Login Security
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-2519 https://www.wordfence.com/threat-intel/vulnerabilities/id/ead87d8b-2659-4e8b-a0b9-138b1db89e36 https://nvd.nist.gov/vuln/detail/CVE-2026-2519

Related records

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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