CVE-2023-29536 – This is a use-after-free vulnerability in Mozil... (How to Fix)

Q: How do I fix CVE-2023-29536?

1. Open the affected application. 2. Go to Help > About Firefox/Thunderbird. 3. Allow the application to check for and install updates. 4. Restart the application when prompted.

Q: What is the severity of CVE-2023-29536?

CVE-2023-29536 has a CVSS score of 8.8 (HIGH). This is a use-after-free vulnerability in Mozilla's memory manager that allows an attacker to cause incorrect pointer freeing, leading to memory corruption or crashes. It affects Firefox, Firefox ESR, Firefox for Android, Focus for Android, and Thunderbird. Attackers could potentially exploit this to execute arbitrary code or cause denial of service.

📋 TL;DR

This is a use-after-free vulnerability in Mozilla's memory manager that allows an attacker to cause incorrect pointer freeing, leading to memory corruption or crashes. It affects Firefox, Firefox ESR, Firefox for Android, Focus for Android, and Thunderbird. Attackers could potentially exploit this to execute arbitrary code or cause denial of service.

💻 Affected Systems

Products:

Firefox
Firefox ESR
Firefox for Android
Focus for Android
Thunderbird

Versions: Firefox < 112, Firefox ESR < 102.10, Firefox for Android < 112, Focus for Android < 112, Thunderbird < 102.10

Operating Systems: Windows, Linux, macOS, Android

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations are vulnerable. No special configuration required for exploitation.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

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

🟠

Likely Case

Application crash (denial of service) or memory corruption that could be leveraged for further exploitation.

🟢

If Mitigated

Application crash with limited impact if sandboxing and other security controls prevent escalation.

🌐 Internet-Facing: HIGH - Web browsers are directly exposed to malicious web content from the internet.

🏢 Internal Only: MEDIUM - Internal users could be targeted via malicious internal websites or documents.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires tricking users to visit malicious websites or open malicious content. Memory corruption vulnerabilities in browsers are frequently exploited in the wild.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Firefox 112, Firefox ESR 102.10, Firefox for Android 112, Focus for Android 112, Thunderbird 102.10

Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2023-13/

Restart Required: Yes

Instructions:

1. Open the affected application. 2. Go to Help > About Firefox/Thunderbird. 3. Allow the application to check for and install updates. 4. Restart the application when prompted.

🔧 Temporary Workarounds

Disable JavaScript

all

Temporarily disable JavaScript to prevent exploitation via malicious web content.

about:config -> javascript.enabled = false

Use alternative browser

all

Switch to an unaffected browser until patches are applied.

🧯 If You Can't Patch

Restrict access to untrusted websites and email content
Implement application whitelisting to prevent execution of malicious payloads

🔍 How to Verify

Check if Vulnerable:

Check the version in Help > About Firefox/Thunderbird and compare with affected versions.

Check Version:

firefox --version or thunderbird --version

Verify Fix Applied:

Verify version is equal to or greater than Firefox 112, Firefox ESR 102.10, Firefox for Android 112, Focus for Android 112, or Thunderbird 102.10.

📡 Detection & Monitoring

Log Indicators:

Application crash logs with memory access violations
Unexpected process termination

Network Indicators:

Connections to known malicious domains serving exploit code

SIEM Query:

EventID=1000 OR EventID=1001 (Application Error) AND ProcessName="firefox.exe" OR ProcessName="thunderbird.exe"

📊 Metadata

CVE ID: CVE-2023-29536

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-416

Published: June 2, 2023

Last Updated: November 21, 2024

🔗 References

https://bugzilla.mozilla.org/show_bug.cgi?id=1821959 Issue Tracking,Permissions Required,Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-13/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-14/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-15/ Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1821959 Issue Tracking,Permissions Required,Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-13/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-14/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2023-15/ Vendor Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2023-29536, you might also want to check these: