ApostropheCMS: Stored XSS via SVG SMIL URI-list scheme-policy bypass

{
  "id": "9384476e6c61972df235e75a9a0783bc45dcb22f91ff154ef3f585214333f5d9",
  "url": "https://osv.dev/vulnerability/CVE-2026-84371",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ApostropheCMS: Stored XSS via SVG SMIL URI-list scheme-policy bypass",
    "summary": "ApostropheCMS is an open-source Node.js content management system, and sanitize-html provides a simple HTML sanitizer with a clear API. From version 1.9.0 until version 2.17.7, packages/sanitize-html/index.js validates an animation value attribute as one flat URL and does not recognize that attributeName selecting href or xlink:href gives the sibling values, from, to, or by attribute SVG SMIL URL semantics. In configurations that allow the animate, animateColor, animateMotion, animateTransform, or set elements, a values list can begin with a safe fragment and contain a later executable destination that survives allowedSchemesAppliedToAttributes checking. When the sanitized SVG is rendered, the browser can copy that later destination into the live link, and a victim who activates the link can execute script in the application's origin. This issue is fixed in version 2.17.7.",
    "evidence": "osv:CVE-2026-84371",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-84371",
      "aliases": [
        "CVE-2026-84371",
        "GHSA-g8qq-57p8-ggw5"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/apostrophecms/apostrophe",
              "type": "GIT",
              "events": [
                {
                  "introduced": "c2e454f69e303c35fc6faae9b86332c2467bc3e2"
                },
                {
                  "fixed": "72f4531e7b491738049eec423d0c1c2342828e5f"
                },
                {
                  "fixed": "1135516a1a4a8f9638641c460488a43d8af20081"
                },
                {
                  "fixed": "38ff1106c8176b16c2da9872acd9b449adcbb949"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "1.9.0"
                      },
                      {
                        "fixed": "2.17.7"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "1135516a1a4a8f9638641c460488a43d8af20081"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "38ff1106c8176b16c2da9872acd9b449adcbb949"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-84371.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:33.633981534Z",
      "provider": "osv",
      "references": [
        "https://github.com/apostrophecms/apostrophe/blob/main/packages/sanitize-html/CHANGELOG.md",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84371.json",
        "https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-g8qq-57p8-ggw5",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-84371",
        "https://github.com/apostrophecms/apostrophe/commit/1135516a1a4a8f9638641c460488a43d8af20081",
        "https://github.com/apostrophecms/apostrophe/commit/38ff1106c8176b16c2da9872acd9b449adcbb949",
        "https://github.com/apostrophecms/apostrophe/pull/5552"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84371.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-84371",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 501020,
  "published_at": "2026-09-01T20:51:10.441+00:00"
}