HTML violations and where to find them

Abstract

With the increased interest in the web in the 90s, everyone wanted to have their own website. However, given the lack of knowledge, such pages contained numerous HTML specification violations. This was when browser vendors came up with a new feature - error tolerance. This feature, part of browsers ever since, makes the HTML parsers tolerate and instead fix violations temporarily. On the downside, it risks security issues like Mutation XSS and Dangling Markup. In this paper, we asked, do we still need to rely on error tolerance, or can we abandon this security issue?