Libsixel prior to v1.8.3 contains a stack buffer overflow in the function gif_process_raster at fromgif.c.
bitbucket.org/netbsd/pkgsrc/commits/a27113e21179cbfbfae0c35f6a9edd6aa498faae
cwe.mitre.org/data/definitions/121.html
github.com/saitoha/libsixel/blob/master/ChangeLog
github.com/saitoha/libsixel/commit/7808a06b88c11dbc502318cdd51fa374f8cd47ee
github.com/saitoha/libsixel/issues/75
github.com/saitoha/libsixel/releases/tag/v1.8.5