CVE-2023-4576

What it actually does

Integer overflow in RecordedSourceSurfaceCreation on Windows leads to heap buffer overflow, enabling sensitive data leakage and potential sandbox escape in affected Mozilla products.

Why it matters to the business

Attackers could access sensitive user data or bypass browser isolation on Windows systems running vulnerable Firefox or Thunderbird versions, increasing risk of data exposure without requiring user interaction.

How an attack unfolds

An attacker delivers crafted content that triggers the integer overflow during surface creation in the browser's rendering process on Windows, overflowing a heap buffer to leak data or escape the sandbox.

How to fix it

Upgrade Firefox to 117 or later, Firefox ESR to 102.15 or 115.2 or later, and Thunderbird to 102.15 or 115.2 or later. Apply updates immediately on Windows systems.

How to confirm the fix worked

Verify installed versions meet or exceed the fixed releases listed in remediation guidance and confirm no vulnerable builds remain in the environment.

Typical attack path

1. Deliver malicious webpage or email attachment to Windows user running vulnerable Firefox/Thunderbird
2. Trigger RecordedSourceSurfaceCreation with oversized parameters causing integer overflow
3. Overwrite adjacent heap memory to leak sensitive data or achieve code execution outside sandbox

How to detect it

Review browser process logs and crash reports for anomalies during content rendering on Windows; correlate with network requests delivering unexpected media or graphics data.

What your security team should do

• Prioritize patching all Windows instances of Firefox and Thunderbird within the next 48 hours due to potential sandbox escape
• Disable automatic media or WebGL processing where feasible until patches are applied
• Monitor for browser crashes or unusual process behavior on Windows endpoints