ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to 7.1.2-9 and 6.9.13-34, there is a vulnerability in ImageMagick’s Magick++ layer that manifests when Options::fontFamily is invoked with an empty string. Clearing a font family calls RelinquishMagickMemory on _drawInfo-font, freeing the font string but leaving _drawInfo-font pointing to freed memory while _drawInfo-family is set to that (now-invalid) pointer.

Any later cleanup or reuse of _drawInfo-font re-frees or dereferences dangling memory. DestroyDrawInfo and other setters (Options::font, Image::font) assume _drawInfo-font remains valid, so destruction or subsequent updates trigger crashes or heap corruption. This vulnerability is fixed in 7.1.2-9 and 6.9.13-34.