CVE-2023-29536

What it actually does

Use-after-free in the memory manager allows an attacker-controlled pointer to be incorrectly freed, leading to memory corruption, assertion failures, or exploitable crashes.

Why it matters to the business

Users of affected browsers and email clients face risk of remote code execution or denial of service when interacting with malicious web content, potentially exposing sensitive data or disrupting operations across large user bases.

How an attack unfolds

An attacker crafts malicious web content that triggers the use-after-free condition in the memory manager. When a user visits the page or opens the crafted content, the browser incorrectly frees attacker-controlled memory, enabling memory corruption that can be leveraged for code execution.

How to fix it

Upgrade Firefox to version 112 or later, Firefox ESR to 102.10 or later, Firefox for Android and Focus for Android to 112 or later, and Thunderbird to 102.10 or later. Apply updates immediately given the high severity and remote attack vector.

How to confirm the fix worked

Verify installed versions meet or exceed the fixed releases listed in remediation guidance; test that the memory manager no longer accepts attacker-controlled pointers for free operations by reviewing release notes and running browser security test suites.

Typical attack path

1. Attacker hosts malicious webpage or email attachment targeting the memory manager flaw
2. Victim opens the content in an affected browser or Thunderbird version
3. Memory manager frees attacker-controlled pointer, causing corruption
4. Attacker chains corruption into arbitrary code execution or crash

How to detect it

Review browser crash logs and memory dumps for patterns consistent with use-after-free in the memory manager; correlate with web request logs showing visits to suspicious domains around the time of crashes.

What your security team should do

• Prioritize patching all instances of affected Mozilla products to the versions specified
• Monitor EPSS and KEV status for any future changes indicating increased exploitation risk
• Enforce automatic updates for browsers and email clients across the organization