Firefox iOS Repeated URL Scheme Trigger (Prompt Abuse) Fixed in 155.1
CVE-2026-86853 Published on September 8, 2026
Repeated external URL scheme launches could potentially cause a denial of service in Firefox for iOS
A malicious webpage could repeatedly trigger external URL schemes, causing system prompts or external application launches. This could make Firefox for iOS temporarily unusable until the page is closed. This vulnerability was fixed in Firefox for iOS 155.1.
Vulnerability Analysis
CVE-2026-86853 can be exploited with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a small impact on availability.
Weakness Type
User Interface (UI) Misrepresentation of Critical Information
The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.
Products Associated with CVE-2026-86853
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Affected Versions
Mozilla Firefox for iOS:- Version 155.1, <= * is unaffected.