In remarkable 1.7.1, lib/parser_inline.js mishandles URL filtering, which allows attackers to trigger XSS via unprintable characters, as demonstrated by a \x0ejavascript: URL.

lib/common/html_re.js in remarkable 1.7.1 allows Regular Expression Denial of Service (ReDoS) via a CDATA section.

Remarkable is a markdown parser. In versions 1.6.2 and lower, remarkable allows the use of `data:` URIs in links and can therefore execute javascript.

Certain input when passed into remarkable before 1.4.1 will bypass the bad protocol check that disallows the javascript: scheme allowing for javascript: url's to be injected into the rendered content.