CVE-2024-1556

What it actually does

Incorrect NULL check on an object inside the built-in profiler permits invalid memory access and undefined behavior when the profiler is active.

Why it matters to the business

When the profiler feature is enabled, the application may crash or allow memory corruption that could be leveraged for code execution, potentially disrupting user sessions or exposing data on affected systems.

How an attack unfolds

An attacker enables or triggers the built-in profiler, supplies input that exercises the faulty NULL check, and causes an out-of-bounds or NULL dereference that results in memory corruption; successful exploitation then depends on the resulting undefined behavior being turned into a controlled read or write primitive.

How to fix it

Upgrade to Firefox 123 or later to receive the corrected NULL check logic; disable the profiler when not required as a temporary mitigation.

How to confirm the fix worked

Confirm the installed application reports version 123 or higher; exercise the profiler under controlled conditions and verify no crash or undefined behavior occurs.

Typical attack path

1. Enable or force the built-in profiler to run
2. Craft input that reaches the incorrect NULL check path
3. Trigger invalid memory access leading to corruption
4. Leverage the resulting primitive for further exploitation or denial of service

How to detect it

Review application crash logs and memory dumps for profiler-related NULL dereference signatures; correlate with any unexpected profiler activation events in telemetry or logs.

What your security team should do

• Prioritize patching all instances to version 123 or newer
• Audit configurations that leave the profiler enabled by default
• Monitor for any post-patch profiler-related crashes as a sign of incomplete remediation