In the ReadDCMImage function in coders/dcm.c in ImageMagick before 7.0.7-23, each redmap, greenmap, and bluemap variable can be overwritten by a new pointer. The previous pointer is lost, which leads to a memory leak. This allows remote attackers to cause a denial of service. https://nvd.nist.gov/vuln/detail/CVE-2018-6405
