In libImaging/PcxDecode.c in Pillow before 7.1.0, an out-of-bounds read can occur when reading PCX files where state->shuffle is instructed to read beyond state->buffer.
github.com/python-pillow/Pillow/commit/6a83e4324738bb0452fbe8074a995b1c73f08de7#diff-9478f2787e3ae9668a15123b165c23ac
github.com/python-pillow/Pillow/commits/master/src/libImaging
github.com/python-pillow/Pillow/pull/4538
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BEBCPE4F2VHTIT6EZA2YZQZLPVDEBJGD/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HOKHNWV2VS5GESY7IBD237E7C6T3I427/
pillow.readthedocs.io/en/stable/releasenotes/7.1.0.html
usn.ubuntu.com/4430-1/
usn.ubuntu.com/4430-2/