The Affinity by Canva application for macOS before 3.3.1 (October 2026 release) did not validate image dimensions against the size of the pixel data when generating QuickLook thumbnails and previews of Affinity document files, leading to an out-of-bounds heap read. A threat actor could craft an Affinity document that, when displayed or previewed by a user in Finder, could disclose the contents of adjacent heap memory in the rendered thumbnail or preview image, or cause the thumbnail or preview extension to crash.