CVE-2026-57388: Hydra Booking Stored XSS Vulnerability

CVE-2026-57388 Overview

CVE-2026-57388 is a stored cross-site scripting (XSS) vulnerability in the Themefic Hydra Booking plugin for WordPress. The flaw affects all versions of the hydra-booking plugin up to and including 1.1.44. It stems from improper neutralization of user-supplied input during web page generation, categorized under [CWE-79]. An attacker can inject malicious JavaScript that persists in the application and executes in the browser context of users who view the affected pages. Successful exploitation requires user interaction and can lead to session hijacking, credential theft, and unauthorized actions within the WordPress site.

Critical Impact
Attackers can store malicious scripts that execute in administrator or user browsers, enabling account takeover, defacement, and privilege escalation on WordPress sites running vulnerable Hydra Booking installations.

Affected Products

Themefic Hydra Booking WordPress plugin (hydra-booking)
All versions from n/a through 1.1.44
WordPress sites with the plugin installed and enabled

Discovery Timeline

2026-07-13 - CVE CVE-2026-57388 published to NVD
2026-07-13 - Last updated in NVD database

Technical Details for CVE-2026-57388

Vulnerability Analysis

The vulnerability is a stored XSS flaw in the Hydra Booking plugin's input handling. User-supplied data is written to the database and later rendered in web pages without proper sanitization or output encoding. Because the payload is persistent, every user who loads the affected page executes the attacker's script within the site's origin.

The attack vector is network-based and requires no privileges to inject the payload in scenarios where booking-related input fields are exposed to unauthenticated users. Exploitation requires a victim to view the poisoned page, and the scope is changed, meaning the injected script can affect resources beyond the vulnerable component. Impact spans confidentiality, integrity, and availability at a limited level. The EPSS probability is 0.18%.

Root Cause

The root cause is improper neutralization of input during web page generation. The plugin fails to apply WordPress escaping functions such as esc_html(), esc_attr(), or wp_kses() on stored booking data before rendering it in the DOM. This allows attacker-controlled HTML and JavaScript to be interpreted by the browser rather than treated as literal text.

Attack Vector

An attacker submits crafted input containing JavaScript through a booking form field or other user-controllable parameter processed by Hydra Booking. The payload is persisted in the WordPress database. When an administrator or another user opens the booking record, listing, or dashboard, the browser parses the stored script and executes it in the site's origin context. Because scope changes upon execution, session cookies, CSRF tokens, and administrative actions can be reached from the compromised page. See the Patchstack WordPress Vulnerability advisory for additional technical context.

Detection Methods for CVE-2026-57388

Indicators of Compromise

Booking records or plugin database tables containing <script>, onerror=, onload=, or javascript: strings.
Unexpected outbound requests from administrator browsers to unfamiliar domains after viewing booking pages.
New or modified WordPress administrator accounts created shortly after booking submissions.
Anomalous session activity or unauthorized plugin and theme installations following visits to booking dashboards.

Detection Strategies

Review Hydra Booking database tables for HTML tags, event handlers, and encoded script payloads in text fields.
Deploy a Web Application Firewall (WAF) rule set that inspects POST requests to Hydra Booking endpoints for XSS payload patterns.
Monitor WordPress access logs for suspicious POST requests to booking submission URLs followed by administrator page views.
Enable Content Security Policy (CSP) reporting to capture script executions from unexpected sources.

Monitoring Recommendations

Alert on modifications to WordPress user roles, options, and plugin files during or after booking form activity.
Track browser telemetry from administrator sessions for script executions originating from booking pages.
Correlate WordPress audit logs with endpoint telemetry to identify follow-on actions after XSS triggers.

How to Mitigate CVE-2026-57388

Immediate Actions Required

Update the Hydra Booking plugin to a version later than 1.1.44 as soon as the vendor releases a patched release.
Disable or remove the hydra-booking plugin if a fixed version is not yet available and booking functionality is not required.
Audit existing booking records for stored payloads and sanitize or delete suspicious entries.
Force password resets and session invalidation for all WordPress administrators if exploitation is suspected.

Patch Information

Refer to the Patchstack advisory for Hydra Booking for the current patch status and fixed version guidance. At publication, versions through 1.1.44 remain vulnerable.

Workarounds

Restrict access to booking submission endpoints using IP allowlisting or authentication where feasible.
Deploy a WAF rule that blocks HTML tags and JavaScript event handlers in Hydra Booking form parameters.
Enforce a strict Content Security Policy (CSP) on the WordPress site to limit inline script execution.
Limit administrator browsing of booking data until the plugin is patched or removed.

bash

# Configuration example
# Disable the vulnerable plugin via WP-CLI until a patched version is available
wp plugin deactivate hydra-booking
wp plugin status hydra-booking