CVE-2025-55030 is a vulnerability identified in Mozilla Firefox for iOS versions prior to 142. The issue arises because Firefox for iOS does not correctly respect the Content-Disposition HTTP header when it is set to 'Attachment' for certain MIME types. Instead of prompting the user to download the content as intended, the browser incorrectly renders the content inline. This behavior can lead to Cross-Site Scripting (XSS) attacks, where malicious scripts embedded in the content could execute within the browser context. The vulnerability is classified under CWE-640, which relates to improper handling of content types and disposition headers, leading to security policy bypasses. The CVSS v3.1 base score is 6.1 (medium severity), with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), scope changed (S:C), and low impact on confidentiality and integrity (C:L/I:L), with no impact on availability (A:N). No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability could be exploited by tricking a user into visiting a maliciously crafted webpage or link that serves content with a manipulated Content-Disposition header, leading to inline execution of potentially harmful scripts within Firefox for iOS.

For European organizations, this vulnerability poses a moderate risk primarily to users who access corporate or sensitive web resources via Firefox on iOS devices. The incorrect handling of Content-Disposition headers could allow attackers to execute XSS attacks, potentially leading to session hijacking, data theft, or unauthorized actions performed on behalf of the user. This is particularly concerning for sectors with high regulatory requirements such as finance, healthcare, and government, where data confidentiality and integrity are critical. Since Firefox for iOS is used by a segment of mobile users, the attack surface includes employees using personal or corporate iPhones and iPads. The vulnerability could be exploited through phishing campaigns or malicious websites, which are common attack vectors in Europe. However, the requirement for user interaction (clicking a link or visiting a malicious page) and the medium severity score suggest that while impactful, the threat is not critical. The scope change in the CVSS vector indicates that the vulnerability could affect resources beyond the initial vulnerable component, potentially impacting other parts of the browser or web applications accessed through it.

European organizations should prioritize updating Firefox for iOS to version 142 or later once a patch is released by Mozilla. In the interim, organizations can implement the following mitigations: 1) Educate users about the risks of clicking unknown or suspicious links, especially on mobile devices. 2) Employ mobile device management (MDM) solutions to enforce browser updates and restrict installation of unapproved applications. 3) Use web filtering and secure web gateways to block access to known malicious URLs that could exploit this vulnerability. 4) Implement Content Security Policy (CSP) headers on corporate web applications to reduce the impact of potential XSS attacks. 5) Monitor network traffic for unusual activity that could indicate exploitation attempts. 6) Encourage the use of alternative browsers on iOS that are not affected until the Firefox patch is available. These steps go beyond generic advice by focusing on organizational controls, user awareness, and layered defenses specific to the mobile iOS environment.