ImageMagick has memory leak of watermark Image object in ReadSTEGANOImage on multiple error/early-return paths

Summary In ReadSTEGANOImage coders/stegano.c, the watermark Image object is not freed on three early-return paths, resulting in a definite memory leak 13.5KB+ per invocation that can be exploited for denial of service. Direct leak of 13512 bytes in 1 objects allocated from: 0 0x7f5c11e27887 in...