CVE-2026-15948 in Hydra Booking Plugin
Summary
by MITRE • 08/15/2026
The Hydra Booking — Appointment Scheduling & Booking Calendar plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'first_name' parameter in all versions up to, and including, 1.2.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with host-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The tfhb_host role required to exploit this vulnerability can be self-assigned by any visitor via the plugin's public Signup shortcode, making this effectively exploitable by unauthenticated users who complete the registration flow.
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Analysis
by VulDB Data Team • 08/15/2026
The Hydra Booking plugin for WordPress presents a critical stored cross-site scripting vulnerability that undermines the security posture of affected installations. This flaw exists in versions up to and including 1.2.2 and stems from inadequate input sanitization and output escaping mechanisms within the plugin's handling of user-submitted data. The vulnerability specifically targets the 'first_name' parameter, which when improperly processed allows malicious script injection into the application's data storage. The technical implementation fails to properly validate or escape user input before storing it in the database, creating a persistent vector for XSS attacks that can affect any user who accesses pages containing the injected content.
The operational impact of this vulnerability extends beyond typical authentication requirements due to the plugin's design allowing unauthenticated users to escalate their privileges through the public Signup shortcode functionality. The tfhb_host role, which serves as the minimum privilege level required to exploit this vulnerability, can be self-assigned by any visitor during the registration process, effectively removing the need for legitimate authentication credentials. This design flaw transforms what might otherwise be a limited authenticated attack vector into a fully exploitable scenario for any internet user who interacts with the plugin's public-facing registration interface. The stored nature of the vulnerability means that once malicious input is injected and saved, it persists in the database and executes automatically whenever affected pages are accessed by any user with appropriate permissions.
This vulnerability directly maps to CWE-79: Improper Neutralization of Input During Web Page Generation, which classifies the issue as a classic cross-site scripting flaw where user-supplied data is inadequately sanitized before being rendered in web pages. The ATT&CK framework categorizes this under T1566.001: Phishing, as the vulnerability enables attackers to craft malicious pages that can be delivered to unsuspecting users through the booking calendar functionality. The attack chain typically involves an attacker registering with the plugin's public interface, leveraging the self-assigning host role privilege, injecting malicious scripts into the first_name field, and then waiting for legitimate users to view pages containing this data. The persistence of stored XSS makes this particularly dangerous as it can affect multiple users over time without requiring repeated exploitation attempts.
Mitigation strategies should focus on immediate patching of the plugin to version 1.2.3 or later, which contains the necessary input sanitization and output escaping fixes. Administrators must also implement comprehensive input validation at multiple layers including client-side and server-side processing, with particular attention to all user-submitted fields that may be displayed in web interfaces. The principle of least privilege should be enforced by restricting which roles can access specific functionality within the plugin, and by removing or disabling the public registration feature that allows self-assignment of elevated privileges. Additional protective measures include implementing Content Security Policy headers, regular security auditing of plugin installations, and monitoring for suspicious user registration patterns or unusual data submissions that might indicate exploitation attempts. Organizations should also consider implementing web application firewalls to detect and block known XSS attack patterns targeting this specific vulnerability class.