CVE-2025-70458 is a DOM-based Cross-Site Scripting (XSS) vulnerability identified in the DomainCheckerApp class within the domain/script.js file of Sourcecodester Domain Availability Checker version 1.0. The root cause is the unsafe use of the innerHTML property in the createResultElement method, which directly injects user-supplied data into the DOM without proper sanitization or encoding. This improper handling allows an attacker to craft malicious input that, when processed by the application, executes arbitrary JavaScript in the victim's browser context. DOM-based XSS differs from traditional reflected or stored XSS in that the vulnerability exists entirely on the client side, exploiting the way the client-side script processes data. The vulnerability can lead to session hijacking, theft of sensitive information, unauthorized actions on behalf of the user, or distribution of malware. Although no public exploits are currently known, the vulnerability is publicly disclosed and thus could be targeted by attackers. The absence of a CVSS score requires an evaluation based on the nature of the vulnerability: it affects confidentiality and integrity, is easy to exploit since it requires only crafted input and no authentication, and can impact all users interacting with the vulnerable component. The vulnerability is specific to Sourcecodester Domain Availability Checker v1.0, a tool used to check domain name availability, which may be integrated into various web services or used by domain registrars and hosting providers.

For European organizations, the impact of CVE-2025-70458 could be significant if the vulnerable software is deployed in public-facing web applications or internal tools. Exploitation could lead to unauthorized access to user sessions, theft of credentials, or execution of malicious scripts that compromise user data and trust. This could result in data breaches, reputational damage, and potential regulatory penalties under GDPR if personal data is exposed. Organizations involved in domain registration, hosting, or web services that utilize Sourcecodester Domain Availability Checker or similar vulnerable components are at higher risk. The vulnerability could also be leveraged as a stepping stone for more complex attacks, such as phishing campaigns or lateral movement within networks. Since the vulnerability does not require authentication and can be triggered by user interaction with the domain search feature, the attack surface includes any user accessing the affected application. The lack of known exploits in the wild suggests limited current impact but also highlights the importance of proactive mitigation to prevent future exploitation.

To mitigate CVE-2025-70458, organizations should immediately review and update the affected code to avoid using innerHTML for rendering user-supplied data. Instead, use safer DOM manipulation methods such as textContent or createElement with proper attribute setting to prevent script execution. Implement rigorous input validation and output encoding on all user inputs, especially those reflected in the DOM. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS attacks. Conduct thorough security testing, including automated and manual DOM-based XSS detection, before deploying updates. If patching the Sourcecodester Domain Availability Checker is not immediately possible, consider isolating or disabling the vulnerable functionality temporarily. Educate developers on secure coding practices related to client-side scripting and DOM manipulation. Monitor web application logs and user reports for suspicious activity that may indicate exploitation attempts. Finally, maintain an incident response plan tailored to web application attacks to respond swiftly if exploitation occurs.