w3m through 0.5.3 is prone to an infinite recursion flaw in HTMLlineproc0 because the feed_table_block_tag function in table.c does not prevent a negative indent value.
https://usn.ubuntu.com/3555-2/
https://usn.ubuntu.com/3555-1/
https://lists.debian.org/debian-lts-announce/2020/04/msg00025.html
https://github.com/tats/w3m/issues/88
https://github.com/tats/w3m/commit/8354763b90490d4105695df52674d0fcef823e92
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00028.html