The vulnerability CVE-2025-55030 affects Firefox for iOS by ignoring Content-Disposition headers specifying 'Attachment' for certain MIME types. This causes content intended for download to be rendered inline, potentially enabling XSS attacks. The flaw was addressed and fixed in Firefox for iOS version 142 as per Mozilla's security advisory MFSA2025-68. The CVSS 3.1 base score is 6.1, reflecting a network attack vector with low attack complexity, no privileges required, user interaction needed, and impacts on confidentiality and integrity with no impact on availability.

An attacker could exploit this vulnerability to execute cross-site scripting attacks by tricking the browser into displaying malicious content inline rather than downloading it. This could lead to partial compromise of confidentiality and integrity of user data within the browser context. There are no reports of active exploitation in the wild. The impact is rated medium based on the CVSS score and vendor advisory.

Mozilla has released an official fix for this vulnerability in Firefox for iOS version 142. Users and administrators should update to this version or later to remediate the issue. Since the vulnerability is fixed, no additional mitigation steps are required beyond applying the update.