CVE-2024-7527 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: How do I fix CVE-2024-7527?

1. Open affected application. 2. Go to Help > About Firefox/Thunderbird. 3. Allow automatic update check and installation. 4. Restart the application when prompted.

Q: What is the severity of CVE-2024-7527?

CVE-2024-7527 has a CVSS score of 8.8 (HIGH). This CVE describes a use-after-free vulnerability in Mozilla's garbage collection mechanism that could allow an attacker to execute arbitrary code or cause a crash. It affects Firefox, Firefox ESR, and Thunderbird browsers. Attackers could exploit this by tricking users into visiting malicious websites.

📋 TL;DR

This CVE describes a use-after-free vulnerability in Mozilla's garbage collection mechanism that could allow an attacker to execute arbitrary code or cause a crash. It affects Firefox, Firefox ESR, and Thunderbird browsers. Attackers could exploit this by tricking users into visiting malicious websites.

💻 Affected Systems

Products:

Firefox
Firefox ESR
Thunderbird

Versions: Firefox < 129, Firefox ESR < 115.14, Firefox ESR < 128.1, Thunderbird < 128.1, Thunderbird < 115.14

Operating Systems: Windows, Linux, macOS, Android, iOS

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations of affected versions are vulnerable. No special settings required for exploitation.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise, data theft, or ransomware deployment.

🟠

Likely Case

Browser crash (denial of service) or limited memory corruption leading to information disclosure.

🟢

If Mitigated

Minimal impact if browsers are fully patched and security controls like sandboxing are effective.

🌐 Internet-Facing: HIGH - Web browsers are inherently internet-facing and process untrusted content.

🏢 Internal Only: MEDIUM - Internal users could be targeted via phishing or compromised internal sites.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires user interaction (visiting malicious website) but no authentication. No public exploit code identified at disclosure.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Firefox 129+, Firefox ESR 115.14+, Firefox ESR 128.1+, Thunderbird 128.1+, Thunderbird 115.14+

Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2024-33/

Restart Required: Yes

Instructions:

1. Open affected application. 2. Go to Help > About Firefox/Thunderbird. 3. Allow automatic update check and installation. 4. Restart the application when prompted.

🔧 Temporary Workarounds

Disable JavaScript

all

Temporarily disable JavaScript to prevent exploitation via malicious websites.

about:config -> javascript.enabled = false

Use alternative browser

all

Switch to a non-affected browser until patches are applied.

🧯 If You Can't Patch

Implement network filtering to block known malicious domains and restrict browser usage to trusted sites only.
Enable enhanced security features like sandboxing and disable unnecessary browser extensions.

🔍 How to Verify

Check if Vulnerable:

Check browser 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 patched versions: Firefox 129+, Firefox ESR 115.14+, Firefox ESR 128.1+, Thunderbird 128.1+, Thunderbird 115.14+.

📡 Detection & Monitoring

Log Indicators:

Browser crash reports with memory access violations
Unexpected process termination in system logs

Network Indicators:

Connections to suspicious domains followed by browser crashes

SIEM Query:

source="browser_logs" AND (event="crash" OR event="access_violation") AND version<"129"

📊 Metadata

CVE ID: CVE-2024-7527

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: August 6, 2024

Last Updated: March 18, 2025

🔗 References

https://bugzilla.mozilla.org/show_bug.cgi?id=1871303 Issue Tracking,Permissions Required
https://www.mozilla.org/security/advisories/mfsa2024-33/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-34/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-35/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-37/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-38/ Vendor Advisory

📤 Share & Export

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🔗 Related Vulnerabilities

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