CVE-2021-45910

What it actually does

Heap-based buffer overflow in the main function allowing an attacker to write attacker-controlled data outside the allocated buffer with partial control over the target address and write length.

Why it matters to the business

Local code execution or application crashes on systems that process untrusted GIF files with this conversion utility, potentially leading to compromise of developer or build machines that rely on the tool.

How an attack unfolds

An attacker crafts a specially malformed GIF file that triggers the heap overflow during conversion; the victim runs gif2apng on the file, allowing the attacker-controlled data to corrupt memory and achieve arbitrary code execution.

How to fix it

Remove or replace gif2apng with a maintained alternative; if a patched build becomes available, upgrade to the fixed version; avoid processing untrusted GIF inputs with this utility.

How to confirm the fix worked

Confirm the installed version is not 1.9, run the tool against known-good and known-bad test files to verify absence of overflow behavior, and monitor for any upstream patches.

Typical attack path

1. Craft malicious GIF file exploiting the buffer overflow
2. Deliver the file to a target system via email, download, or shared storage
3. Trick the user or automated process into invoking gif2apng on the file
4. Trigger heap corruption to execute attacker-supplied code

How to detect it

Search process execution logs and file-access records for invocations of gif2apng against files originating from untrusted sources; look for abnormal memory or crash dumps associated with the binary.

What your security team should do

• Inventory all systems using gif2apng and remove the binary where possible
• Block execution of gif2apng via application allow-listing
• Replace the utility with a supported image-conversion library or tool
• Educate developers on risks of unmaintained open-source utilities