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)

{
  "id": "0175b5bb8cac4ffc52d9e51f05aa150730c3725dbc0cd7d925c430af84fd5916",
  "url": "https://osv.dev/vulnerability/GHSA-mrv2-3pqr-j5jr",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "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": "### 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 `` 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 `` that was already loading when you built the live tree cannot fire after `sanitize()` returns.\" That does not hold when the detached node is not the hook's own node. ### Tested versions - 3.4.16 (latest) and main at 18f8f0e - also 3.4.15, 3.4.12 and 2.5.8 jsdom for the matrix below, and Chromium (Playwright) for the event actually firing. ### Details `src/purify.ts` line 2134 (`dist/purify.cjs.js` line 2009 in 3.4.16), `_handleHookDetachedNode()`: ```js if (currentNode === root || getParentNode(currentNode) !== null) { return false; } if (IN_PLACE) { _neutralizeSubtree(currentNode); } ``` It only checks whether `currentNode` lost its parent. When a hook removes `currentNode.parentNode` (or any ancestor), `currentNode` still has a parent, so nothing happens. The rest of the removed subtree is no longer reachable by the walker, and it is not in `DOMPurify.removed`, so the post walk pass does not see it either. The same happens when a hook removes a",
    "evidence": "osv:GHSA-mrv2-3pqr-j5jr",
    "products": [
      {
        "name": {
          "value": "dompurify",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "3.4.17",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-mrv2-3pqr-j5jr",
      "aliases": [
        "CVE-2026-116803",
        "GHSA-mrv2-3pqr-j5jr"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "3.4.17"
                }
              ]
            }
          ],
          "package": {
            "name": "dompurify",
            "purl": "pkg:npm/dompurify",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-mrv2-3pqr-j5jr/GHSA-mrv2-3pqr-j5jr.json",
            "last_known_affected_version_range": "<= 3.4.16"
          }
        }
      ],
      "modified": "2026-10-27T10:56:05.613459690Z",
      "provider": "osv",
      "references": [
        "https://github.com/cure53/DOMPurify/security/advisories/GHSA-mrv2-3pqr-j5jr",
        "https://github.com/cure53/DOMPurify/pull/1672",
        "https://github.com/cure53/DOMPurify/commit/a77a3e78b59f72fa4d1c83f22e121ad9cc7d3575",
        "https://github.com/cure53/DOMPurify",
        "https://github.com/cure53/DOMPurify/releases/tag/3.4.17"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-693",
          "CWE-79"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-22T16:24:52Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-116803",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 461502,
  "published_at": "2026-10-22T16:24:52+00:00"
}