ApostropheCMS sanitize-html: SMIL animation namespace-prefix bypass allows javascript: URI injection (XSS)

{
  "id": "3a87f40c4ca7d584bf71d86a42b373c89da9abbba94586cc909aeefd6a260724",
  "url": "https://osv.dev/vulnerability/GHSA-374f-7chj-9948",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ApostropheCMS sanitize-html: SMIL animation namespace-prefix bypass allows javascript: URI injection (XSS)",
    "summary": "## Summary sanitize-html 2.17.7 introduced `animatesUrlAttribute()` to block SVG animation elements (`animate`, `animateColor`, `animateMotion`, `animateTransform`, `set`) when their `attributeName` targets a URL sink like `href`. However, this check is bypassed when the animation element uses a namespace prefix (e.g., `svg:animate` instead of `animate`). ## Root Cause The `animatesUrlAttribute` function (index.js, line ~832) checks `svgAnimationTags.indexOf(name.toLowerCase())`, where `svgAnimationTags` contains bare local names: `[\"animate\", \"animatecolor\", \"animatemotion\", \"animatetransform\", \"set\"]`. htmlparser2 passes namespace-prefixed tag names verbatim, so `svg:animate` does not match `animate` in the array, causing the function to return `false` and skip the SMIL XSS protection. Ironically, the function already handles namespace prefixes correctly for the `attributeName` target value (line ~843): `const localName = target.slice(target.lastIndexOf(\":\") + 1)` — but this same stripping was not applied to the tag name itself. ## Proof of Concept ```javascript const sanitizeHtml = require(\"sanitize-html\"); const config = { allowedTags: false, allowedAttributes: false, allowedSchemes: [\"http\", \"https\"] }; // Standard animate — BLOCKED by 2.17.7 fix const blocked = sanitizeHtml( `Click`, config ); console.log(\"Standard animate:\", blocked.includes(\"javascript:\") ? \"BYPASS\" : \"BLOCKED\"); // Output: BLOCKED // Namespace-prefixed animate — BYPASSES the fix const bypassed = sani",
    "evidence": "osv:GHSA-374f-7chj-9948",
    "products": [
      {
        "name": {
          "value": "sanitize-html",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.18.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "low",
    "structured": {
      "id": "GHSA-374f-7chj-9948",
      "aliases": [
        "CVE-2026-113657",
        "GHSA-374f-7chj-9948"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "2.17.7"
                },
                {
                  "fixed": "2.18.0"
                }
              ]
            }
          ],
          "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-374f-7chj-9948/GHSA-374f-7chj-9948.json"
          }
        }
      ],
      "modified": "2026-10-20T18:30:03.591034807Z",
      "provider": "osv",
      "references": [
        "https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-374f-7chj-9948",
        "https://github.com/apostrophecms/apostrophe/commit/9500b8b0e1d630d5e07fbb5fd2c25ed0943845ce",
        "https://github.com/apostrophecms/apostrophe/commit/f84fd41cbf6c22eb8d0008fc9c25df1f7130b350",
        "https://github.com/apostrophecms/apostrophe",
        "https://github.com/apostrophecms/apostrophe/releases/tag/sanitize-html@2.18.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "severity": "LOW",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-20T18:21:19Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-113657",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 390147,
  "published_at": "2026-10-20T18:21:19+00:00"
}