CVE-2026-2792 – Memory safety vulnerabilities in Mozilla Firefo... (How to Fix)

Q: How do I fix CVE-2026-2792?

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

Q: What is the severity of CVE-2026-2792?

CVE-2026-2792 has a CVSS score of 9.8 (CRITICAL). Memory safety vulnerabilities in Mozilla Firefox and Thunderbird could allow memory corruption attacks. With sufficient effort, attackers could exploit these bugs to execute arbitrary code on affected systems. This impacts Firefox versions below 148 and Firefox ESR versions below 140.8.

📋 TL;DR

Memory safety vulnerabilities in Mozilla Firefox and Thunderbird could allow memory corruption attacks. With sufficient effort, attackers could exploit these bugs to execute arbitrary code on affected systems. This impacts Firefox versions below 148 and Firefox ESR versions below 140.8.

💻 Affected Systems

Products:

Firefox
Firefox ESR
Thunderbird
Thunderbird ESR

Versions: Firefox < 148, Firefox ESR < 140.8

Operating Systems: All supported platforms

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 ransomware deployment.

🟠

Likely Case

Browser crashes or instability; potential for limited code execution in targeted attacks.

🟢

If Mitigated

Minimal impact if systems are patched promptly and have additional security controls.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: HIGH

Exploitation requires significant effort but is possible via crafted web content or emails.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Firefox 148, Firefox ESR 140.8

Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2026-13/

Restart Required: Yes

Instructions:

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

🔧 Temporary Workarounds

Disable JavaScript

all

Temporarily reduces attack surface by disabling JavaScript execution.

about:config -> javascript.enabled = false

🧯 If You Can't Patch

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

🔍 How to Verify

Check if Vulnerable:

Check browser version in About dialog; if Firefox < 148 or Firefox ESR < 140.8, it is vulnerable.

Check Version:

firefox --version

Verify Fix Applied:

Confirm version is Firefox ≥ 148 or Firefox ESR ≥ 140.8 after update.

📡 Detection & Monitoring

Log Indicators:

Browser crash logs with memory access violations
Unexpected process termination

Network Indicators:

Suspicious downloads or connections following browser crashes

SIEM Query:

source="firefox.log" AND ("crash" OR "segmentation fault")

📊 Metadata

CVE ID: CVE-2026-2792

CVSS v3 Score: 9.8 (CRITICAL)

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

CWE: CWE-787

Published: February 24, 2026

Last Updated: February 25, 2026

🔗 References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=2008912%2C2010050%2C2010275%2C2012331 Broken Link
https://www.mozilla.org/security/advisories/mfsa2026-13/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-15/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-16/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-17/ Vendor Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

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