CVE-2025-46198 is a Cross Site Scripting (XSS) vulnerability identified in the Grav CMS versions 1.7.46, 1.7.47, and 1.7.48. Grav is a flat-file content management system widely used for building websites without a traditional database backend. The vulnerability arises from improper sanitization of user-supplied input that is reflected in the onerror attribute of the HTML img element. An attacker can craft a malicious payload embedded within an image tag's onerror attribute, which executes arbitrary JavaScript code when the image fails to load or triggers the error event. This type of XSS is classified as a reflected or stored XSS depending on how the payload is injected and rendered. Exploiting this vulnerability allows an attacker to execute arbitrary scripts in the context of the victim's browser session, potentially leading to session hijacking, credential theft, defacement, or redirection to malicious sites. The vulnerability affects specific Grav versions, indicating that the issue likely stems from a regression or insufficient input validation in these releases. No official patch links or CVSS score have been published yet, and there are no known exploits in the wild at the time of this report. However, given the nature of XSS vulnerabilities, exploitation is generally straightforward if the attacker can control input that is reflected in the vulnerable attribute. The lack of a CVSS score suggests that the vulnerability is newly disclosed and pending further assessment.

For European organizations using Grav CMS versions 1.7.46 through 1.7.48, this vulnerability poses a significant risk to the confidentiality and integrity of their web applications and user data. Successful exploitation can lead to theft of user credentials, session tokens, or other sensitive information, enabling further compromise of user accounts or administrative access. It can also facilitate phishing attacks by injecting malicious scripts that alter website content or redirect users to fraudulent sites. This can damage organizational reputation, lead to regulatory non-compliance (e.g., GDPR violations due to data breaches), and cause operational disruptions. Since Grav is often used by small to medium enterprises, educational institutions, and public sector websites in Europe, the impact could be widespread if unpatched. The vulnerability does not directly affect availability but could indirectly cause denial of service through defacement or user lockout. The absence of known exploits in the wild currently reduces immediate risk, but the ease of exploitation typical of XSS vulnerabilities means attackers may develop exploits rapidly once the vulnerability becomes public knowledge.

European organizations should immediately assess their Grav CMS installations to determine if they are running affected versions (1.7.46, 1.7.47, or 1.7.48). Until an official patch is released, organizations should implement the following mitigations: 1) Employ Web Application Firewalls (WAFs) with rules to detect and block malicious payloads targeting the onerror attribute or suspicious script injections in image tags. 2) Sanitize and validate all user inputs rigorously, especially those that can be reflected in HTML attributes, using server-side input validation libraries or custom filters. 3) Implement Content Security Policy (CSP) headers to restrict the execution of inline scripts and reduce the impact of XSS attacks. 4) Monitor web server logs and application behavior for unusual requests or error events that could indicate exploitation attempts. 5) Educate developers and administrators about secure coding practices to prevent similar vulnerabilities in future releases. Once a vendor patch is available, prioritize testing and deploying it promptly. Additionally, consider isolating or restricting access to vulnerable Grav instances until remediation is complete.