ApostropheCMS sanitize-html: unbounded recursion when re-sanitizing the fallback of a discarded iframe (stack overflow, nestingLimit not enforced)

{
  "id": "a7590271bf4c1e863205d9ce57c5d253220f6060d393389031470aa1ed42d197",
  "url": "https://osv.dev/vulnerability/GHSA-c9rx-x947-fp3h",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ApostropheCMS sanitize-html: unbounded recursion when re-sanitizing the fallback of a discarded iframe (stack overflow, nestingLimit not enforced)",
    "summary": "### Summary Since 2.18.0, when an `` is not allowed and `disallowedTagsMode` is `'discard'` (the defaults), its raw-text content is re-sanitized by a recursive call to `sanitizeHtml(text, options)` (the change from #5564, fixing #5550). The recursion has no bound and starts each nested call with a fresh state. Two consequences, both absent from 2.17.7 and 2.17.4: 1. A few kilobytes of unclosed `<iframe>` tags throw `RangeError: Maximum call stack size exceeded` with the default options. Any application that sanitizes untrusted HTML with 2.18.0 can be made to throw on a small crafted input. 2. `nestingLimit` is not enforced across a discarded iframe: each nested iframe restarts the depth count at zero, so the output can be nested arbitrarily deep regardless of the configured limit. ### Affected versions - 2.18.0 (the current `latest`), and the `main` branch at the time of writing (the recursive call is still in `packages/sanitize-html/index.js`, in the `ontext` handler, branch `tag === 'iframe' && !tagAllowed(tag) && options.disallowedTagsMode === 'discard'`). - Not affected: 2.17.7 and 2.17.4 (tested with the same inputs below). Tested with Node.js v26.7.0. ### Reproduction 1: stack overflow with the default options ```js const sanitizeHtml = require('sanitize-html'); // with 2.18.0: sanitizeHtml('<iframe>'.repeat(1000)); // 8,000 chars: returns '' sanitizeHtml('<iframe>'.repeat(2000)); // 16,000 chars: throws RangeError: Maximum call stack size exceeded sanitizeHtml('<iframe",
    "evidence": "osv:GHSA-c9rx-x947-fp3h",
    "products": [
      {
        "name": {
          "value": "sanitize-html",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.18.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-c9rx-x947-fp3h",
      "aliases": [
        "CVE-2026-113650",
        "GHSA-c9rx-x947-fp3h"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "2.18.0"
                },
                {
                  "fixed": "2.18.1"
                }
              ]
            }
          ],
          "package": {
            "name": "sanitize-html",
            "purl": "pkg:npm/sanitize-html",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-c9rx-x947-fp3h/GHSA-c9rx-x947-fp3h.json"
          }
        }
      ],
      "modified": "2026-10-21T17:15:08.634885273Z",
      "provider": "osv",
      "references": [
        "https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-c9rx-x947-fp3h",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-113650",
        "https://github.com/apostrophecms/apostrophe/commit/06e4b377f3c360f9e89c32dccd7e505ad5ddf498",
        "https://github.com/apostrophecms/apostrophe/commit/40b989b1a9dd23d30029b8ce7668634265cfe5ea",
        "https://github.com/apostrophecms/apostrophe",
        "https://github.com/apostrophecms/apostrophe/releases/tag/sanitize-html@2.18.1"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-674"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-20T17:17:35Z",
        "github_reviewed_at": "2026-10-21T17:05:01Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-113650",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 397035,
  "published_at": "2026-10-21T17:05:01+00:00"
}