DOMPurify SAFE_FOR_TEMPLATES bypass: split template expressions survive in attached shadow root content on DOM output modes
## Summary
When DOMPurify is configured with `SAFE_FOR_TEMPLATES: true` together with a DOM-returning mode (`RETURN_DOM: true`, `RETURN_DOM_FRAGMENT: true`, or `IN_PLACE: true`), template expressions such as `{{...}}`, `${...}`, and `<%...%>` survive sanitization inside the text content of an attached shadow root. The post-walk safety net `_scrubTemplateExpressions` (`src/purify.ts:1717`) was extended to recurse into `<template>.content`, but it never recurses into attached shadow roots. An attacker who can supply a DOM node carrying a shadow root (the `IN_PLACE` and shadow-aware `RETURN_DOM` surfaces) can split an expression across text nod
DOMPurify IN_PLACE: hook that removes a parent or sibling leaves the detached subtree's event handlers armed (incomplete fix for GHSA-p98j-92pf-mc4p)
### Summary
The 3.4.16 fix for GHSA-p98j-92pf-mc4p only covers a hook that removes the node it was called for. If an `IN_PLACE` hook removes a different node, like the current node's parent or a sibling that has not been visited yet, that subtree is never walked or neutralized. Event handlers in it stay on the elements, and an `<img onerror>` that was already loading fires after `sanitize()` returns.
The README says: "Nodes that a hook detaches from the tree ... are treated as removed. In IN_PLACE mode their subtree is neutralized inline, so an `<img onload>` that was already loading when you built the live tree cannot fire after `sanitize(
DOMPurify: SMIL attributeName=href guard is skipped when PARSER_MEDIA_TYPE is application/xhtml+xml
### Summary
DOMPurify drops `attributeName` attributes whose value contains `href`, so an allowed `<animate>` or `<set>` can't rewrite a link's href after sanitizing. The check compares the attribute name after `transformCaseFunc`, and that function doesn't lowercase in XHTML mode. In XHTML the attribute is spelled `attributeName`, so the comparison with `"attributename"` never matches and the guard does nothing.
An app that uses `PARSER_MEDIA_TYPE: 'application/xhtml+xml'` and allows `animate` and `attributeName` will keep `<animate attributeName="href" values="x;javascript:alert(1)">`. Clicking the parent link then runs the script.
This
DOMPurify before 3.4.16 XSS via IN_PLACE Returned Rawtext Root
DOMPurify before 3.4.16 contains a cross-site scripting vulnerability that allows attackers to bypass sanitization because IN_PLACE mode returns a force-removed style element whose text content still carries markup. Attackers can supply a style element containing a closing style tag and an img onerror payload, which executes script when the application serializes and re-parses the returned node.
DOMPurify from 3.4.13 before 3.4.16 DOM XSS via IN_PLACE afterSanitize Hooks
DOMPurify from 3.4.13 before 3.4.16 contains a cross-site scripting vulnerability because IN_PLACE mode fails to neutralize subtrees detached by afterSanitizeElements or afterSanitizeAttributes hooks. Attackers can supply markup with on* handlers inside a wrapper removed by such hooks, leaving handlers armed on the live DOM to execute script in the victim origin.