malformed HTML causes a regex backtracking lockup

Try execute following code in node.js v8.7.0 repl:

const a =`<g>
<g>
<path fill="#ffffff"/>
</g>
<path fill="#ffffff"/>`

var HTML_BLOCK_ELEMENT_R = /^ *<([^ >/]+) ?([^>]*)\/{0}>(?=[\s\S]*<\/\1>)((?:[\s\S]*?(?:<\1[^>]*>[\s\S]*?<\/\1>)*[\s\S]*?)*?)<\/\1>\n*/

HTML_BLOCK_ELEMENT_R.exec(a)

node.js will hang at last command

[hugmanrique]

Please read https://www.regular-expressions.info/catastrophic.html, we’ve run into a catastrofic backtrack.

[probablyup]

Released as 6.5.0