w3m through 0.5.3 does not properly handle temporary files when the ~/.w3m directory is unwritable, which allows a local attacker to craft a symlink attack to overwrite arbitrary files.
lists.opensuse.org/opensuse-security-announce/2019-04/msg00028.html
www.securityfocus.com/bid/102855
bugs.debian.org/888097
github.com/tats/w3m/commit/18dcbadf2771cdb0c18509b14e4e73505b242753
salsa.debian.org/debian/w3m/commit/18dcbadf2771cdb0c18509b14e4e73505b242753
usn.ubuntu.com/3555-1/
usn.ubuntu.com/3555-2/