CVE-2023-29535

What it actually does

Memory corruption occurs when weak maps are accessed before correct tracing after garbage collector compaction, leading to a potentially exploitable crash.

Why it matters to the business

Users of affected browsers and email clients face application instability or denial of service, with possible remote code execution risk that could lead to data loss or system compromise across large user bases.

How an attack unfolds

An attacker hosts a malicious webpage that triggers repeated garbage collector compaction cycles while manipulating weak map references, causing the browser to dereference untraced memory and crash or execute attacker-controlled code.

How to fix it

Upgrade Firefox to version 112 or later, Firefox ESR to 102.10 or later, Focus for Android to 112 or later, Firefox for Android to 112 or later, and Thunderbird to 102.10 or later.

How to confirm the fix worked

Verify installed product versions meet or exceed the fixed releases listed above and monitor for crash reports involving garbage collector and weak map handling.

Typical attack path

1. Victim visits attacker-controlled webpage or receives malicious email
2. JavaScript triggers garbage collector compaction
3. Weak map access occurs before tracing completes
4. Memory corruption is induced leading to crash or code execution

How to detect it

Search browser crash logs and telemetry for entries involving garbage collector compaction and weak map access failures; correlate with web browsing history to suspicious domains.

What your security team should do

• Immediately deploy updates to all affected Mozilla products
• Prioritize browser updates for high-risk user populations
• Enable automatic updates where possible
• Review crash telemetry for related memory corruption signatures