See $URL for a rundown and links to individual issues. Wide range from client-side to server-side; memory corruption, overflows, denial of service. Fixes for most but not all are included in the latest 3.6.x. We have only 2.74.x and 3.4.x in the tree. Ongoing discussion about backporting to 2.74 here: https://gitlab.gnome.org/GNOME/libsoup/-/merge_requests/449