CVE-2024-25165

What it actually does

Global buffer overflow in the LineText function at lib/swf5compiler.flex in SWFTools 0.9.2, enabling out-of-bounds memory writes during SWF5 compilation.

Why it matters to the business

Crashes or potential code execution when processing untrusted Flash files, interrupting build pipelines, content conversion, and legacy media workflows that depend on this utility.

How an attack unfolds

An attacker supplies a crafted SWF or source file that reaches the vulnerable LineText routine with excessive data, overflowing the global buffer and potentially hijacking control flow.

How to fix it

Upgrade SWFTools to a version containing a fix for the buffer overflow in lib/swf5compiler.flex; until then, avoid processing untrusted inputs and consider sandboxing or alternative tools.

How to confirm the fix worked

Rebuild with address sanitizers, run regression tests against known overflow-triggering inputs, and verify the LineText function no longer permits out-of-bounds access.

Typical attack path

1. Locate systems or CI jobs invoking SWFTools on external input
2. Prepare malicious SWF5 source triggering oversized LineText content
3. Trigger compilation via the vulnerable binary
4. Leverage overflow for crash or arbitrary code execution

How to detect it

Search process logs and crash dumps for segmentation faults or buffer-overrun signals originating from swf5compiler or LineText during SWF handling.

What your security team should do

• Block or sandbox SWFTools usage on untrusted files until patched
• Track upstream commits addressing the swf5compiler.flex overflow
• Scan build systems for the vulnerable 0.9.2 binary
• Replace SWFTools with maintained alternatives where possible