CVE-2021-40264

What it actually does

NULL pointer dereference in FreeImage_CloneTag allows remote attackers to trigger a crash in applications that process crafted image files with the library.

Why it matters to the business

Applications relying on the library can experience unexpected crashes and service interruptions when handling untrusted image content, increasing operational downtime and support costs until the library is updated.

How an attack unfolds

An attacker creates a specially malformed image file containing metadata that triggers the NULL dereference path inside FreeImage_CloneTag. The file is delivered to a target application that uses the vulnerable library version; when the application loads or displays the image the dereference occurs and the process terminates.

How to fix it

Upgrade FreeImage to version 1.18.0 or later. Rebuild and redeploy any dependent applications after the library update. Where immediate upgrade is not feasible, isolate image-processing components and apply strict input validation or sandboxing around file handling.

How to confirm the fix worked

Confirm the installed FreeImage library version is 1.18.0 or newer. Re-test affected applications with known triggering image samples to verify absence of crashes. Monitor build pipelines to ensure the updated library is linked.

Typical attack path

1. Craft malicious image file with tag data designed to reach FreeImage_CloneTag with a NULL pointer
2. Deliver the file to the victim via web upload, email attachment, or other untrusted input channel
3. Victim application invokes FreeImage to load or manipulate the image
4. Library dereferences NULL pointer and crashes the hosting process

How to detect it

Review application and system logs for segmentation faults or abrupt process terminations occurring during image load operations. Correlate crashes with FreeImage usage by inspecting loaded libraries or stack traces that reference FreeImageTag.cpp.

What your security team should do

• Immediately inventory all products and containers that statically or dynamically link FreeImage and schedule upgrades to 1.18.0+
• Prioritize patching for any internet-facing or high-volume image-processing services
• Add library version checks to vulnerability scanning and SBOM processes
• Consider runtime sandboxing or input filtering for image-handling code until patches are deployed