CVE-2023-51308 identifies a multiple HTML injection vulnerability in PHPJabbers Car Park Booking System version 3.0. The vulnerability arises from insufficient input validation and sanitization in several parameters including 'name', 'plugin_sms_api_key', 'plugin_sms_country_code', and 'title'. An attacker can exploit these injection points by crafting malicious HTML content that is then rendered by the application, potentially leading to cross-site scripting (XSS)-like effects or manipulation of the web interface. The CVSS 3.1 vector indicates the attack can be performed remotely (AV:N) with low attack complexity (AC:L), no privileges required (PR:N), but requires user interaction (UI:R). The scope is changed (S:C), meaning the vulnerability affects components beyond the initially vulnerable component, and impacts confidentiality and integrity to a limited degree (C:L/I:L) without affecting availability (A:N). Although no public exploits are known, the vulnerability could be leveraged for phishing, session hijacking, or defacement attacks. The CWE-80 classification confirms this is a classic HTML injection/XSS type vulnerability. No patches are currently listed, so organizations must rely on input validation and monitoring until official fixes are released.

For European organizations using PHPJabbers Car Park Booking System v3.0, this vulnerability could lead to unauthorized injection of malicious HTML content, potentially enabling phishing attacks, session hijacking, or unauthorized data manipulation. While availability is not impacted, the confidentiality and integrity of user data and system content could be compromised. This may result in reputational damage, regulatory non-compliance (e.g., GDPR concerns), and operational disruptions in car park booking services. Attackers exploiting this vulnerability could target customers or employees by injecting deceptive content, leading to credential theft or unauthorized access. The risk is heightened in sectors relying heavily on automated booking and parking management, such as transportation hubs, municipal services, and large commercial centers prevalent in Europe.

Organizations should implement strict input validation and sanitization on all user-controllable parameters, especially 'name', 'plugin_sms_api_key', 'plugin_sms_country_code', and 'title'. Employing a whitelist approach for allowed characters and encoding output to prevent HTML rendering is critical. Web Application Firewalls (WAFs) can be configured to detect and block suspicious input patterns related to HTML injection. Monitoring logs for unusual input or behavior can help detect exploitation attempts. Since no official patches are currently available, organizations should engage with PHPJabbers support for updates and consider temporary mitigation such as disabling or restricting affected functionalities. Additionally, educating users to recognize phishing attempts and maintaining updated backups will reduce impact if exploitation occurs.