Exploit in Firefox for iOS Affects User Interface and External Launches
CVE-2026-86853

4.3MEDIUM

Key Information:

Vendor

Mozilla
Status
Firefox For iOS
Vendor
CVE Published:
8 September 2026

What is CVE-2026-86853?

A vulnerability in Firefox for iOS could allow a malicious webpage to exploit external URL schemes. This issue may result in persistent system prompts or launches of external applications, rendering the browser temporarily unusable until the offending webpage is closed. It is essential for users to update to Firefox for iOS 155.1, where this issue has been addressed, to maintain a seamless browsing experience and safeguard against repeated disruptions.

Affected Version(s)

Firefox for iOS 155.1

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1847631
https://www.mozilla.org/security/advisories/mfsa2026-89/

CVSS V3.1

Score:
4.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Amit Gajbhare
.