CVE-2021-39592

What it actually does

Null pointer dereference in pool_lookup_uint() within pool.c that causes the application to crash when processing malformed input.

Why it matters to the business

Processing of SWF files halts unexpectedly, interrupting any automated conversion, extraction, or analysis workflows that depend on the affected tool.

How an attack unfolds

An attacker supplies a crafted SWF file to any swftools utility that invokes pool_lookup_uint(); the malformed data reaches the null dereference and terminates the process.

How to fix it

Upgrade to a version of swftools that contains a fix for the null dereference in pool.c; if no patched release is available, replace the tool with a maintained alternative or isolate its execution.

How to confirm the fix worked

Reproduce the crash with known triggering SWF samples before and after the update; inspect pool.c to confirm the pointer check has been added; run regression tests against the full test corpus.

Typical attack path

1. Create or obtain a malformed SWF file designed to reach pool_lookup_uint()
2. Invoke a swftools binary (e.g., swfdump, swfextract) against the file
3. Trigger the null dereference and force an application crash

How to detect it

Review system and application logs for segmentation faults or abrupt termination of swftools processes immediately after SWF file handling; correlate crash timestamps with file-processing job logs.

What your security team should do

• Discontinue processing of untrusted SWF files with swftools until a fixed build is deployed
• Wrap any remaining usage inside a sandbox or container with limited privileges
• Monitor the upstream project for a patched release and apply it promptly