CVE-2021-39587

What it actually does

Null pointer dereference in swf_DumpABC within abc.c causes the swftools process to crash when handling specially crafted input.

Why it matters to the business

Processing of Flash files can be disrupted, halting workflows that depend on swftools and requiring manual intervention to resume operations.

How an attack unfolds

An attacker supplies a malformed SWF file to swftools; when the tool invokes swf_DumpABC the null dereference occurs and the process terminates.

How to fix it

No fixed version is published; replace swftools with an unaffected alternative or isolate its use to trusted input only.

How to confirm the fix worked

Reproduce the crash with a known triggering SWF file before and after any mitigation; inspect source for removal of the dereference in abc.c.

Typical attack path

1. Create malformed SWF file that reaches swf_DumpABC with a null pointer
2. Deliver the file to a system running swftools
3. Invoke swftools on the file (e.g., via command line or automated pipeline)
4. Application crashes resulting in denial of service

How to detect it

Review process crash logs, core dumps, and job-scheduler output for swftools terminations while processing SWF files; correlate with file-origin timestamps.

What your security team should do

• Restrict swftools execution to trusted, sanitized inputs
• Replace swftools with maintained equivalents in all automated pipelines
• Monitor upstream project for any future patches or forks