CVE-2026-2796
📋 TL;DR
A JIT miscompilation vulnerability in Firefox's JavaScript: WebAssembly component could allow arbitrary code execution when processing malicious web content. This affects Firefox versions before 148, potentially compromising user systems through browser-based attacks.
💻 Affected Systems
- Mozilla Firefox
📦 What is this software?
Firefox by Mozilla
Thunderbird 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 sandbox escape enabling limited code execution within browser context.
If Mitigated
Browser crash with no code execution if sandbox holds or exploit fails.
🎯 Exploit Status
Exploitation requires user to visit malicious website or open crafted content.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox 148
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2026-13/
Restart Required: Yes
Instructions:
1. Open Firefox. 2. Click menu → Help → About Firefox. 3. Allow automatic update to version 148. 4. Restart Firefox when prompted.
🔧 Temporary Workarounds
Disable WebAssembly
allTemporarily disable WebAssembly execution in Firefox
about:config → Set javascript.options.wasm to false
Use NoScript extension
allBlock JavaScript/WebAssembly execution on untrusted sites
Install NoScript from addons.mozilla.org
🧯 If You Can't Patch
- Restrict browser usage to trusted websites only
- Implement application whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check Firefox version via about:support or Help → About FirefoxCheck Version:
firefox --versionVerify Fix Applied:
Confirm Firefox version is 148 or higher📡 Detection & Monitoring
Log Indicators:
- Firefox crash reports with WebAssembly-related stack traces
- Unexpected process creation from Firefox
Network Indicators:
- Connections to suspicious domains followed by unusual outbound traffic
SIEM Query:
source="firefox.log" AND ("crash" OR "WebAssembly" OR "wasm")