libImaging/TiffDecode.c in Pillow before 6.2.2 has a TIFF decoding integer overflow, related to realloc.
https://usn.ubuntu.com/4272-1/
https://pillow.readthedocs.io/en/stable/releasenotes/6.2.2.html
https://github.com/python-pillow/Pillow/commit/4e2def2539ec13e53a82e06c4b3daf00454100c4