CVE-2024-9396 – A memory corruption vulnerability in Firefox, F... (How to Fix)

Q: How do I fix CVE-2024-9396?

1. Open the application. 2. Go to Help > About Firefox/Thunderbird. 3. Allow automatic update or download latest version from mozilla.org. 4. Restart the application.

Q: What is the severity of CVE-2024-9396?

CVE-2024-9396 has a CVSS score of 8.8 (HIGH). A memory corruption vulnerability in Firefox, Firefox ESR, and Thunderbird could allow attackers to execute arbitrary code or cause denial of service through structured clone operations. This affects users running vulnerable versions of these Mozilla applications.

📋 TL;DR

A memory corruption vulnerability in Firefox, Firefox ESR, and Thunderbird could allow attackers to execute arbitrary code or cause denial of service through structured clone operations. This affects users running vulnerable versions of these Mozilla applications.

💻 Affected Systems

Products:

Firefox
Firefox ESR
Thunderbird

Versions: Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, Thunderbird < 131

Operating Systems: All platforms supported by affected applications

Default Config Vulnerable: ⚠️ Yes

Notes: All standard installations are vulnerable; no special configuration required.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise, data theft, or malware installation.

🟠

Likely Case

Application crash (denial of service) or limited memory corruption leading to instability.

🟢

If Mitigated

No impact if patched; limited impact if exploit attempts are blocked by security controls.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: HIGH

Exploitation requires triggering specific structured clone conditions; no public exploits known.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Firefox 131+, Firefox ESR 128.3+, Thunderbird 128.3+, Thunderbird 131+

Vendor Advisory: https://www.mozilla.org/security/advisories/

Restart Required: Yes

Instructions:

1. Open the application. 2. Go to Help > About Firefox/Thunderbird. 3. Allow automatic update or download latest version from mozilla.org. 4. Restart the application.

🔧 Temporary Workarounds

Disable JavaScript

all

Prevents exploitation by disabling JavaScript execution in the browser.

about:config -> javascript.enabled = false

🧯 If You Can't Patch

Restrict application usage to trusted websites only.
Implement application whitelisting to block unauthorized execution.

🔍 How to Verify

Check if Vulnerable:

Check application version in Help > About Firefox/Thunderbird.

Check Version:

firefox --version or thunderbird --version

Verify Fix Applied:

Confirm version is Firefox ≥131, Firefox ESR ≥128.3, or Thunderbird ≥128.3/131.

📡 Detection & Monitoring

Log Indicators:

Application crash logs with memory corruption errors
Unexpected structured clone operations

Network Indicators:

Unusual web traffic to malicious sites attempting exploitation

SIEM Query:

source="firefox.log" AND ("crash" OR "memory corruption")

📊 Metadata

CVE ID: CVE-2024-9396

CVSS v3 Score: 8.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE: CWE-119

Published: October 1, 2024

Last Updated: April 4, 2025

🔗 References

https://bugzilla.mozilla.org/show_bug.cgi?id=1912471 Issue Tracking
https://www.mozilla.org/security/advisories/mfsa2024-46/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-47/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-49/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-50/ Vendor Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

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