CVE-2025-14327
📋 TL;DR
This vulnerability allows attackers to spoof download notifications in Firefox and Thunderbird, potentially tricking users into executing malicious files. It affects all users running vulnerable versions of Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR. The spoofing occurs in the Downloads Panel component where attackers can manipulate download prompts.
💻 Affected Systems
- Firefox
- Firefox ESR
- Thunderbird
- Thunderbird ESR
📦 What is this software?
Firefox by Mozilla
Thunderbird by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Users download and execute malicious files believing they are legitimate downloads, leading to full system compromise, data theft, or ransomware infection.
Likely Case
Users are tricked into downloading malicious files that appear legitimate, potentially leading to malware installation or credential theft.
If Mitigated
With proper user awareness and security controls, users would verify downloads through other means, reducing successful exploitation.
🎯 Exploit Status
Exploitation requires user interaction (clicking/downloading) but no authentication. The CWE-290 indicates authentication bypass via spoofing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox 146, Thunderbird 146, Firefox ESR 140.7, Thunderbird 140.7
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2025-92/
Restart Required: Yes
Instructions:
1. Open Firefox/Thunderbird. 2. Click menu → Help → About Firefox/Thunderbird. 3. Allow automatic update check and installation. 4. Restart the application when prompted.
🔧 Temporary Workarounds
Disable automatic downloads
allConfigure browser to ask where to save files for every download
In Firefox: about:preferences → General → Downloads → Check 'Always ask you where to save files'
🧯 If You Can't Patch
- Implement application whitelisting to prevent execution of unauthorized files
- Deploy endpoint protection with file reputation checking and behavioral analysis
🔍 How to Verify
Check if Vulnerable:
Check browser version in About dialog (menu → Help → About Firefox/Thunderbird)Check Version:
firefox --version or thunderbird --versionVerify Fix Applied:
Verify version is at least Firefox 146, Thunderbird 146, Firefox ESR 140.7, or Thunderbird 140.7📡 Detection & Monitoring
Log Indicators:
- Unexpected download prompts from untrusted sources
- Multiple download attempts from same source with different filenames
Network Indicators:
- Unusual download patterns from web servers
- HTTP requests triggering multiple download prompts
SIEM Query:
source="firefox.log" OR source="thunderbird.log" AND (event="download" AND suspicious_filename=*)