The AcquireCacheNexus function in magick/pixel_cache.c in GraphicsMagick before 1.3.28 allows remote attackers to cause a denial of service (heap overwrite) or possibly have unspecified other impact via a crafted image file, because a pixel staging area is not used.
WritePNMImage in coders/pnm.c in GraphicsMagick 1.3.26 allows remote attackers to cause a denial of service (bit_stream.c MagickBitStreamMSBWrite heap-based buffer overflow and application crash) or possibly have unspecified other impact via a crafted file.
coders/wpg.c in GraphicsMagick 1.3.26 allows remote attackers to cause a denial of service (heap-based buffer overflow and application crash) or possibly have unspecified other impact via a crafted file, related to the AcquireCacheNexus function in magick/pixel_cache.c.
The DrawImage function in magick/render.c in GraphicsMagick 1.3.26 does not properly look for pop keywords that are associated with push keywords, which allows remote attackers to cause a denial of service (negative strncpy and application crash) or possibly have unspecified other impact via a crafted file.
The ReadWPGImage function in coders/wpg.c in GraphicsMagick 1.3.26 does not properly validate colormapped images, which allows remote attackers to cause a denial of service (ImportIndexQuantumType invalid write and application crash) or possibly have unspecified other impact via a malformed WPG image.
GraphicsMagick 1.3.26 is vulnerable to a heap-based buffer overflow vulnerability found in the "Display visual image directory" feature of the DescribeImage() function of the magick/describe.c file. One possible way to trigger the vulnerability is to run the identify command on a specially crafted MIFF format file with the verbose flag.