CVE-2015-4491

What it actually does

Integer overflow in make_filter_table during bitmap scaling leads to heap-based buffer overflow enabling arbitrary code execution or application crash.

Why it matters to the business

Applications handling images on Linux systems risk remote compromise or denial of service; the issue is widespread across browsers and desktop environments but has been public for over a decade with no active exploitation campaigns noted.

How an attack unfolds

An attacker creates a bitmap with malicious dimensions that trigger the integer overflow when the image is scaled; the crafted image is delivered through a web page, attachment, or file opened in an affected product such as Firefox or Chrome on Linux, resulting in heap corruption that can be leveraged for code execution.

How to fix it

Upgrade gdk-pixbuf to version 2.31.5 or newer and update affected products including Mozilla Firefox to 40.0 or ESR 38.2 and later; rebuild or reinstall any downstream packages that statically link the library.

How to confirm the fix worked

Verify installed gdk-pixbuf version is at least 2.31.5 and confirm affected applications report current patched releases; test image processing with known trigger dimensions in a controlled environment.

Typical attack path

1. Craft bitmap image with dimensions designed to overflow during filter table creation
2. Deliver image via web content, email attachment, or local file
3. Victim application loads and scales the image using vulnerable gdk-pixbuf
4. Trigger integer overflow in pixops/pixops.c leading to heap buffer overflow
5. Execute arbitrary code or cause crash

How to detect it

Search application crash logs and core dumps for heap corruption patterns during image scaling operations; inspect web server or email gateway logs for delivery of unusual bitmap files around the time of crashes in browser or desktop processes.

What your security team should do

• Prioritize patching of gdk-pixbuf and dependent applications on all Linux endpoints
• Review and update image-handling libraries across desktop and server environments
• Monitor for any new exploit maturity signals given the long public disclosure period