An out-of-bounds write issue has been discovered in the backspace handling of the checkType() function in etc.c within the W3M application. This vulnerability is triggered by supplying a specially crafted HTML file to the w3m binary. Exploitation of this flaw could lead to application crashes, resulting in a denial of service condition.
https://github.com/tats/w3m/pull/273
https://github.com/tats/w3m/issues/268
https://github.com/tats/w3m/commit/edc602651c506aeeb60544b55534dd1722a340d3