CVE-2025-55033 is a cross-site scripting (XSS) vulnerability identified in Mozilla Focus for iOS versions earlier than 142. The flaw arises from improper handling of JavaScript links dragged into the URL bar, which can be exploited to execute arbitrary scripts within the context of the browser. This vulnerability is classified under CWE-79, indicating a failure to properly sanitize or validate user-controllable input before rendering it in a web context. The attack vector is network-based (AV:N), requiring no privileges (PR:N) but does require user interaction (UI:R), specifically the action of dragging a malicious JavaScript link into the URL bar. The scope is changed (S:C), meaning the vulnerability can affect resources beyond the vulnerable component. The impact affects confidentiality and integrity (C:L/I:L) but does not affect availability (A:N). Although no public exploits have been reported, the vulnerability could allow attackers to steal sensitive information, hijack user sessions, or manipulate browser behavior. The vulnerability was published on August 19, 2025, and no patches or mitigations have been officially released at the time of this report. The vulnerability is specific to the iOS platform and the Mozilla Focus browser, which is a privacy-focused browser designed to block trackers and provide a minimalistic browsing experience.

For European organizations, the vulnerability poses a risk primarily to confidentiality and integrity of data accessed via Mozilla Focus on iOS devices. Attackers could leverage this XSS flaw to execute malicious scripts that steal session tokens, credentials, or other sensitive information, potentially leading to unauthorized access to corporate resources or personal data breaches. Since Mozilla Focus is used by privacy-conscious users, including journalists, activists, and professionals handling sensitive information, exploitation could undermine trust and privacy guarantees. The requirement for user interaction limits mass exploitation but targeted phishing or social engineering campaigns could be effective. The vulnerability does not impact availability, so denial-of-service is unlikely. Organizations relying on iOS devices with Mozilla Focus installed should consider the risk to mobile endpoints, especially in sectors like finance, media, and government where data confidentiality is critical.

1. Update Mozilla Focus for iOS to version 142 or later once the patch is released by Mozilla to address this vulnerability. 2. Until a patch is available, educate users to avoid dragging or interacting with suspicious JavaScript links or unknown URLs within the browser. 3. Implement mobile device management (MDM) policies to restrict installation of unapproved browsers or enforce timely updates. 4. Use endpoint protection solutions capable of detecting and blocking malicious scripts or suspicious browser behaviors on iOS devices. 5. Encourage users to enable content security policies or browser settings that limit script execution where possible. 6. Monitor network traffic for unusual activity indicative of XSS exploitation attempts. 7. Conduct phishing awareness training focused on social engineering vectors that could trigger this vulnerability. 8. Consider alternative browsers with robust security controls if Mozilla Focus is not essential.