CVE-2026-2634
📋 TL;DR
This vulnerability in Firefox for iOS allows malicious scripts to desynchronize the address bar from actual web content before a server response arrives. Attackers can present their own pages under spoofed domain names, potentially tricking users into interacting with malicious sites. Only Firefox for iOS users running versions below 147.4 are affected.
💻 Affected Systems
- Firefox for iOS
📦 What is this software?
Firefox by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Users could be tricked into entering sensitive information (passwords, financial data) into attacker-controlled pages that appear to be legitimate websites, leading to credential theft, financial fraud, or malware installation.
Likely Case
Attackers create convincing phishing pages that appear to be legitimate sites (like banks or social media), tricking users into submitting login credentials or personal information.
If Mitigated
With proper user awareness training and browser security features enabled, users might notice inconsistencies or be prompted for suspicious activity, reducing successful exploitation.
🎯 Exploit Status
Exploitation requires user interaction (visiting a malicious website) but no authentication. The vulnerability is in the browser's UI synchronization logic.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 147.4
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2026-12/
Restart Required: Yes
Instructions:
1. Open the App Store on your iOS device. 2. Search for Firefox. 3. Tap 'Update' to install version 147.4 or later. 4. Restart Firefox after update completes.
🔧 Temporary Workarounds
Use alternative browser
allTemporarily switch to a different browser (like Safari or Chrome) until Firefox is updated.
Disable JavaScript
allDisabling JavaScript in Firefox settings may prevent exploitation but will break many websites.
🧯 If You Can't Patch
- Educate users to verify URLs carefully before entering sensitive information
- Implement web filtering to block known malicious domains
🔍 How to Verify
Check if Vulnerable:
Open Firefox on iOS, go to Settings > About Firefox, and check if version is below 147.4.Check Version:
Not applicable for iOS (use Settings menu)Verify Fix Applied:
After updating, confirm version is 147.4 or higher in Settings > About Firefox.📡 Detection & Monitoring
Log Indicators:
- Unusual browser crashes or unexpected domain changes in user browsing patterns
Network Indicators:
- Requests to suspicious domains that don't match address bar URLs
SIEM Query:
Not typically applicable for mobile browser vulnerabilities