CVE-2026-86853

Repeated external URL scheme launches could potentially cause a denial of service in Firefox for iOS

Published Sep 8, 2026 CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Mozilla firefox Mobile
CPEs cpe:2.3:a:mozilla:firefox_mobile:*:*:*:*:*:iphone_os:*:*
Vendors & Products Mozilla firefox Mobile
Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox For Ios
Vendors & Products Mozilla
Mozilla firefox For Ios
Type Values Removed Values Added
Weaknesses CWE-451
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Repeated external URL scheme launches could potentially cause a denial of service in Firefox for iOS
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mozilla
Published
Updated
Sep 8, 2026, 3:48 PM
Reserved
Sep 8, 2026, 3:03 PM
Status
Analyzed
Published
Sep 8, 2026, 4:18 PM
Modified
Oct 5, 2026, 5:09 PM