GHSA-x3q4-9hxx-gx8m

Description

## Summary `sanitize-html` discards the *content* of every element in `nonTextTags`. It delimits that region using htmlparser2's close events, and ignores the `isImplied` flag htmlparser2 passes it. Closing a still-open **ancestor** from inside a `<noscript>` makes htmlparser2 unwind its stack past the `noscript`; the synthetic implied close it emits on the way ends the discard region early, and everything after it is treated as ordinary body content. A browser with scripting enabled parses `<noscript>` content as **raw text**, so the same markup renders as inert text there. The sanitizer therefore emits elements the page itself would not have. ## Reproduction ```js const sanitizeHtml = require("sanitize-html"); sanitizeHtml('<div><noscript></div><img src="http://evil.test/t.gif"></noscript>', { allowedTags: ["div", "img"], allowedAttributes: { img: ["src"] }, nonTextTags: ["script", "style", "textarea", "option", "noscript"], }); // => '<div></div><img src="http://evil.test/t.gif" />' ``` Chrome, given the same input, renders **no** `<img>` — the whole payload is raw text inside the unclosed `<noscript>`. Verified with Playwright, `srcdoc` into an iframe so the scripting flag is on. A `<![CDATA[` variant hides the opening tag from the parser entirely and has the same effect: ``` <p>Hi</p><![CDATA[ x > <noscript>]]><a href="…">Reset your password</a><img src="…beacon.gif"></noscript> ``` htmlparser2 runs a CDATA token to `]]>`; Chrome ends a bogus comment at the first `>`, so the `<noscript>` after it is real to the browser and invisible to the parser. ## Where the behaviour is `index.js`: - `:154` — `nonTextTagsArray` (the default list, `['script','style','textarea','option','xmp']`). - `:638` — `onclosetag: function (name, isImplied)` — receives the flag. - `:644` — `skipTextDepth--` — decrements without consulting `isImplied`. ## Suggested fix Do not end a discard region on an implied close. htmlparser2 already distinguishes them; the flag is passed and discarded. Something close to: ```js onclosetag: function (name, isImplied) { if (skipText) { if (isImplied) return; // an implied close must not end the region skipTextDepth--; … ```