CVE-2026-27388: DesignThemes Booking Manager Auth Bypass

CVE-2026-27388 Overview

CVE-2026-27388 is a missing authorization vulnerability [CWE-862] in the DesignThemes Booking Manager WordPress plugin (designthemes-booking-manager). The flaw affects all versions up to and including 2.0. Incorrectly configured access control security levels allow unauthenticated network attackers to reach plugin functionality that should be restricted. Successful exploitation leads to a high availability impact on the affected WordPress site without requiring user interaction or authentication.

Critical Impact
Unauthenticated attackers can reach restricted plugin endpoints over the network and disrupt site availability, with no privileges or user interaction required.

Affected Products

DesignThemes Booking Manager plugin for WordPress, versions through 2.0
WordPress sites running the designthemes-booking-manager plugin
All deployments where the plugin is active and reachable over the network

Discovery Timeline

2026-03-05 - CVE-2026-27388 published to NVD
2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-27388

Vulnerability Analysis

The vulnerability stems from broken access control in the DesignThemes Booking Manager plugin. The plugin exposes one or more action handlers without verifying the requester's capability or nonce. WordPress plugins typically gate sensitive operations using current_user_can() checks and check_ajax_referer() calls. When these checks are missing or misconfigured, any network client can invoke the affected handlers.

Because the CVSS vector indicates no confidentiality or integrity impact and high availability impact, exploitation likely triggers a state-changing operation that disrupts the booking service or the host site. Examples include destructive actions against booking records, configuration resets, or resource-exhausting operations reachable via plugin AJAX endpoints.

For technical specifics on the affected handler and request shape, see the Patchstack Vulnerability Report.

Root Cause

The plugin fails to enforce authorization on functionality that should require an authenticated, privileged user. Per [CWE-862], the affected code path does not perform a capability check before executing a sensitive action. Routes are registered with broad access, allowing unauthenticated callers to invoke them directly.

Attack Vector

An attacker sends a crafted HTTP request to the vulnerable plugin endpoint on a target WordPress site. The endpoint executes the requested action without validating the caller's identity or permissions. No credentials, session, or user interaction are required. The attack works across the public internet against any WordPress instance running an affected version of the plugin.

No public proof-of-concept code is available at this time. Refer to the vendor advisory for technical details on the request structure.

Detection Methods for CVE-2026-27388

Indicators of Compromise

Unauthenticated POST or GET requests to wp-admin/admin-ajax.php or plugin-specific routes referencing booking manager actions
Unexpected modification, deletion, or resets of booking records, schedules, or plugin configuration
Spikes in 4xx or 5xx responses from /wp-content/plugins/designthemes-booking-manager/ paths
Web server access logs showing repeated requests to plugin action handlers from a single source IP

Detection Strategies

Inventory WordPress installations and identify any using designthemes-booking-manager version 2.0 or earlier
Inspect WordPress access logs for requests targeting plugin AJAX actions without an authenticated session cookie
Correlate booking data anomalies with web request logs to identify unauthorized state changes
Enable WordPress audit logging plugins to capture changes to plugin options and custom post types

Monitoring Recommendations

Forward WordPress and web server logs to a centralized analytics platform for retention and correlation
Alert on bursts of requests to admin-ajax.php originating from unauthenticated sessions
Monitor for unusual administrative operations on booking records outside of business hours
Track plugin version drift across WordPress fleets to detect unpatched instances

How to Mitigate CVE-2026-27388

Immediate Actions Required

Identify all WordPress sites running designthemes-booking-manager and confirm the installed version
Deactivate the plugin on any site running version 2.0 or earlier until a fixed release is verified
Restrict access to wp-admin/admin-ajax.php from untrusted networks where feasible
Review booking and configuration data for unauthorized changes

Patch Information

At the time of publication, the NVD entry lists affected versions through 2.0 with no fixed version specified. Monitor the Patchstack Vulnerability Report and the plugin vendor's release notes for a patched version. Apply the update across all instances once available.

Workarounds

Disable the plugin until a vendor-supplied fix is installed
Deploy a Web Application Firewall (WAF) rule blocking unauthenticated requests to the plugin's action handlers
Restrict access to the WordPress admin and AJAX surface using IP allowlists or authentication at the reverse proxy
Take and verify a recent backup of the WordPress database before applying any changes

bash

# Temporarily disable the plugin via WP-CLI
wp plugin deactivate designthemes-booking-manager

# Confirm deactivation
wp plugin status designthemes-booking-manager