CVE-2023-5172
📋 TL;DR
This CVE describes a use-after-free vulnerability in Firefox's Ion Engine hashtable implementation. An attacker could exploit this to execute arbitrary code or cause a crash. All Firefox users with versions below 118 are affected.
💻 Affected Systems
- Mozilla Firefox
📦 What is this software?
Firefox by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full system compromise, data theft, or ransomware deployment.
Likely Case
Browser crash or denial of service, potentially leading to data loss in active sessions.
If Mitigated
Limited impact if browser sandboxing works as intended, potentially just a tab crash.
🎯 Exploit Status
Exploitation requires JavaScript execution but no authentication. No public exploit code available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox 118 and later
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2023-41/
Restart Required: Yes
Instructions:
1. Open Firefox. 2. Click menu → Help → About Firefox. 3. Firefox will check for updates and install version 118+. 4. Restart Firefox when prompted.
🔧 Temporary Workarounds
Disable JavaScript
allPrevents exploitation by blocking JavaScript execution, but breaks most websites.
about:config → javascript.enabled = false
Use Content Security Policy
allRestrict JavaScript sources to trusted domains only.
Add 'Content-Security-Policy: script-src 'self'' to web server headers
🧯 If You Can't Patch
- Isolate Firefox usage to non-critical systems with no sensitive data
- Implement network filtering to block known malicious domains and JavaScript sources
🔍 How to Verify
Check if Vulnerable:
Check Firefox version in About Firefox dialog. If version is less than 118, system is vulnerable.Check Version:
firefox --version (Linux/macOS) or check Help → About Firefox (all platforms)Verify Fix Applied:
Confirm Firefox version is 118 or higher in About Firefox dialog.📡 Detection & Monitoring
Log Indicators:
- Firefox crash reports with Ion Engine references
- Unexpected browser termination events
Network Indicators:
- Unusual JavaScript loading patterns
- Requests to known exploit domains
SIEM Query:
source="firefox.log" AND ("crash" OR "segfault") AND "ion"🔗 References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1852218
- https://security.gentoo.org/glsa/202401-10
- https://www.mozilla.org/security/advisories/mfsa2023-41/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1852218
- https://security.gentoo.org/glsa/202401-10
- https://www.mozilla.org/security/advisories/mfsa2023-41/
