CVE-2025-63061 is a DOM-based Cross-site Scripting (XSS) vulnerability identified in the hogash Kallyas WordPress theme, affecting versions up to and including 4.22.0. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, specifically within client-side scripts that handle dynamic content rendering. This flaw allows an attacker to inject malicious JavaScript code into the victim’s browser environment by manipulating input parameters that are not properly sanitized or encoded before being incorporated into the DOM. Unlike traditional reflected or stored XSS, DOM-based XSS occurs entirely on the client side, making detection and mitigation more challenging. Exploitation typically involves tricking users into clicking crafted URLs or interacting with malicious content that triggers the vulnerable script. The injected script can execute arbitrary actions such as stealing session cookies, performing actions on behalf of the user, or redirecting users to phishing or malware sites. Although no public exploits have been reported yet, the vulnerability is publicly disclosed and thus may attract attackers. The affected product, Kallyas, is a popular multipurpose WordPress theme used by many businesses and organizations for their websites. Since the vulnerability does not require authentication, any visitor to a compromised site could be targeted. The lack of a CVSS score means severity must be assessed based on impact and exploitability factors. The vulnerability impacts confidentiality and integrity primarily, with potential availability impact if exploited for defacement or redirection. The scope is limited to websites using the affected theme versions. Mitigation currently requires patching when a fix is released or implementing defensive controls such as input validation, output encoding, and CSP enforcement.

For European organizations, the impact of CVE-2025-63061 can be significant, especially for those relying on the Kallyas theme for public-facing websites, including e-commerce, media, and corporate portals. Successful exploitation can lead to theft of user credentials and session tokens, enabling account takeover and unauthorized access to sensitive information. This undermines user trust and can result in reputational damage and regulatory penalties under GDPR if personal data is compromised. Additionally, attackers may use the vulnerability to inject malicious content, leading to phishing attacks or malware distribution targeting European users. The integrity of website content can be compromised, potentially affecting business operations and customer confidence. While the vulnerability does not directly impact backend systems, the client-side compromise can serve as a foothold for broader attacks. Given the widespread use of WordPress and the popularity of the Kallyas theme, many small and medium enterprises across Europe could be exposed, increasing the overall risk landscape.

1. Monitor for official patches or updates from hogash and apply them promptly once available to remediate the vulnerability. 2. Until patches are released, implement strict input validation and output encoding on all user-controllable inputs that influence DOM generation within the theme’s scripts. 3. Deploy a robust Content Security Policy (CSP) that restricts the execution of inline scripts and limits sources of executable code to trusted domains. 4. Use Web Application Firewalls (WAFs) with custom rules to detect and block suspicious input patterns indicative of XSS attempts targeting the Kallyas theme. 5. Conduct regular security audits and penetration testing focusing on client-side vulnerabilities in the web application. 6. Educate website administrators and developers about the risks of DOM-based XSS and secure coding practices. 7. Encourage users to employ security-conscious browsing habits and use updated browsers with built-in XSS protections. 8. Consider temporarily disabling or replacing vulnerable theme features that handle dynamic input until a fix is applied.