XSS can occur in GNOME Web (aka Epiphany) before 40.4 and 41.x before 41.1 when View Source mode or Reader mode is used, as demonstrated by a a page title.
{ "ubuntu_priority": "medium", "availability": "No subscription required", "binaries": [ { "binary_name": "epiphany-browser", "binary_version": "3.36.4-0ubuntu2" }, { "binary_name": "epiphany-browser-data", "binary_version": "3.36.4-0ubuntu2" }, { "binary_name": "epiphany-browser-dbgsym", "binary_version": "3.36.4-0ubuntu2" } ] }
{ "ubuntu_priority": "medium", "availability": "No subscription required", "binaries": [ { "binary_name": "epiphany-browser", "binary_version": "42.1-1" }, { "binary_name": "epiphany-browser-data", "binary_version": "42.1-1" }, { "binary_name": "epiphany-browser-dbgsym", "binary_version": "42.1-1" } ] }