CVE-2023-51299 identifies an HTML Injection vulnerability in PHPJabbers Hotel Booking System version 4.0. The vulnerability affects multiple input parameters such as name, plugin_sms_api_key, plugin_sms_country_code, and title. HTML Injection, classified under CWE-79, allows attackers to inject arbitrary HTML code into web pages viewed by other users. This can lead to various attacks including cross-site scripting (XSS) variants, phishing, or UI redressing. The vulnerability is remotely exploitable over the network (AV:N) with low attack complexity (AC:L), requires no privileges (PR:N), but does require user interaction (UI:R), such as clicking a malicious link or visiting a crafted page. The scope is changed (S:C), indicating that exploitation can affect resources beyond the vulnerable component. The impact affects confidentiality and integrity partially (C:L/I:L) but does not affect availability (A:N). No patches or known exploits are currently available, but the vulnerability is publicly disclosed as of February 19, 2025. The lack of a patch increases the urgency for organizations to implement mitigations. The vulnerability is significant for web applications handling sensitive booking and customer data, as injected HTML could be used to steal session tokens, redirect users, or manipulate displayed content.

For European organizations, particularly those in the hospitality and travel sectors using PHPJabbers Hotel Booking System, this vulnerability poses a risk to customer data confidentiality and the integrity of booking information. Attackers could exploit the HTML Injection to conduct phishing attacks, steal session cookies, or manipulate booking details, potentially leading to financial fraud or reputational damage. Given the widespread use of online booking systems in Europe’s tourism-dependent economies, exploitation could disrupt business operations and erode customer trust. The vulnerability does not directly impact system availability but could facilitate further attacks that compromise broader system security. Organizations processing personal data under GDPR must consider the compliance implications of data breaches resulting from this vulnerability.

Organizations should immediately review and sanitize all user inputs for the affected parameters (name, plugin_sms_api_key, plugin_sms_country_code, title) to ensure that HTML or script code cannot be injected. Implement strict output encoding on all user-supplied data before rendering it in the browser to prevent execution of injected HTML. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts. Monitor web application logs for unusual input patterns or repeated injection attempts. If possible, isolate the booking system from other critical infrastructure to limit potential lateral movement. Engage with PHPJabbers for official patches or updates and apply them promptly once available. Conduct regular security assessments and penetration testing focused on injection vulnerabilities. Educate staff and users about phishing risks associated with malicious links that could exploit this vulnerability.