CVE-2023-4055
📋 TL;DR
This vulnerability in Firefox causes cookie jar inconsistencies when domain cookie limits are exceeded, potentially sending requests with missing cookies. This affects Firefox versions below 116, Firefox ESR below 102.14, and Firefox ESR below 115.1. The issue could impact session management and authentication mechanisms.
💻 Affected Systems
- Mozilla Firefox
- Mozilla Firefox ESR
📦 What is this software?
Firefox by Mozilla
Firefox by Mozilla
Firefox by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Authentication bypass or session hijacking if critical authentication cookies are omitted from requests, allowing unauthorized access to user accounts or sensitive data.
Likely Case
Session disruption or logout events when authentication cookies fail to transmit properly, causing user inconvenience and potential data loss in web applications.
If Mitigated
Minimal impact with proper session validation and redundant authentication mechanisms in place, though users may experience intermittent login issues.
🎯 Exploit Status
Exploitation requires specific conditions with many cookies per domain, making reliable weaponization challenging but possible with targeted attacks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox 116, Firefox ESR 102.14, Firefox ESR 115.1
Vendor Advisory: https://bugzilla.mozilla.org/show_bug.cgi?id=1782561
Restart Required: Yes
Instructions:
1. Open Firefox. 2. Click menu → Help → About Firefox. 3. Allow automatic update download and installation. 4. Restart Firefox when prompted.
🔧 Temporary Workarounds
Limit cookies per domain
allConfigure websites to use fewer cookies per domain to avoid triggering the vulnerability
Use alternative browsers
allSwitch to updated versions of other browsers until Firefox is patched
🧯 If You Can't Patch
- Implement server-side session validation that doesn't rely solely on cookies
- Use additional authentication factors beyond cookie-based sessions
🔍 How to Verify
Check if Vulnerable:
Check Firefox version via menu → Help → About Firefox. If version is below 116 (or ESR below specified versions), system is vulnerable.Check Version:
firefox --versionVerify Fix Applied:
After update, verify version shows Firefox 116+ or ESR 102.14+/115.1+ in About Firefox dialog.📡 Detection & Monitoring
Log Indicators:
- Unexpected session timeouts
- Authentication failures despite valid credentials
- Cookie-related errors in browser console
Network Indicators:
- HTTP requests missing expected cookie headers
- Increased authentication requests from same users
SIEM Query:
source="firefox.log" AND ("session timeout" OR "authentication failed" OR "cookie error")🔗 References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1782561
- https://lists.debian.org/debian-lts-announce/2023/08/msg00008.html
- https://lists.debian.org/debian-lts-announce/2023/08/msg00010.html
- https://www.debian.org/security/2023/dsa-5464
- https://www.debian.org/security/2023/dsa-5469
- https://www.mozilla.org/security/advisories/mfsa2023-29/
- https://www.mozilla.org/security/advisories/mfsa2023-30/
- https://www.mozilla.org/security/advisories/mfsa2023-31/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1782561
- https://lists.debian.org/debian-lts-announce/2023/08/msg00008.html
- https://lists.debian.org/debian-lts-announce/2023/08/msg00010.html
- https://www.debian.org/security/2023/dsa-5464
- https://www.debian.org/security/2023/dsa-5469
- https://www.mozilla.org/security/advisories/mfsa2023-29/
- https://www.mozilla.org/security/advisories/mfsa2023-30/
- https://www.mozilla.org/security/advisories/mfsa2023-31/
