CVE-2025-55028 is a vulnerability identified in Mozilla Firefox for iOS versions earlier than 142. The issue arises from the ability of malicious web pages to execute repetitive JavaScript alert() calls, which can effectively lock the browser interface by continuously prompting alert dialogs. This behavior prevents users from interacting with the browser or the underlying device until the alerts are dismissed, resulting in a denial of service (DoS) condition. The vulnerability is classified under CWE-400, which relates to uncontrolled resource consumption leading to DoS. The attack vector is network-based, requiring no privileges but does require user interaction to trigger the alerts. The CVSS v3.1 base score is 6.5, reflecting medium severity with no impact on confidentiality or integrity but a high impact on availability. There are currently no known exploits in the wild, and no official patches have been linked at the time of publication. The vulnerability specifically affects Firefox on iOS, which limits the scope to Apple mobile devices running this browser. The repetitive alert dialogs can be triggered by visiting a malicious or compromised website, making this a client-side attack that can disrupt user productivity and potentially impact business operations relying on mobile browser access. The lack of patches means users should exercise caution and consider temporary mitigations until an update is released.

For European organizations, this vulnerability primarily threatens the availability of Firefox for iOS on employee and customer devices. Organizations relying on Firefox for iOS for web applications, remote access portals, or customer-facing services may experience user disruption or loss of productivity due to the denial of service condition. While the vulnerability does not compromise data confidentiality or integrity, the inability to use the browser can delay critical tasks and communications. Sectors with mobile-dependent workflows, such as finance, healthcare, and government services, could see operational impacts. Additionally, customer-facing services accessed via Firefox on iOS could suffer reputational damage if users encounter persistent browser lockups. The absence of known exploits reduces immediate risk, but the ease of exploitation via web content means attackers could weaponize this vulnerability in phishing campaigns or malicious websites. The impact is thus moderate but non-negligible, especially in environments with high iOS device usage and Firefox browser adoption.

1. Update Firefox for iOS to version 142 or later as soon as the patch is released by Mozilla to fully remediate the vulnerability. 2. Until patches are available, consider restricting or disabling JavaScript execution in Firefox for iOS through browser settings or mobile device management (MDM) policies where feasible, especially on devices used for sensitive or critical operations. 3. Educate users about the risks of visiting untrusted websites and the potential for malicious scripts causing browser lockups; encourage reporting of suspicious behavior. 4. Implement network-level web filtering to block access to known malicious or suspicious domains that could host exploit code. 5. For organizations with custom web applications, test compatibility with alternative browsers on iOS to provide fallback options if Firefox is affected. 6. Monitor user reports and device logs for signs of repeated alert dialogs or browser crashes to detect potential exploitation attempts. 7. Coordinate with IT and security teams to prepare incident response plans addressing mobile browser DoS scenarios.