ApostropheCMS: Stored XSS via Unescaped Widget Style Attribute Serialization

{
  "id": "43f80dcb2a9e59d4302270cd59098a797c20a4d8bb852af3d45dad126f8157fd",
  "url": "https://osv.dev/vulnerability/GHSA-7jg5-frgc-c67w",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ApostropheCMS: Stored XSS via Unescaped Widget Style Attribute Serialization",
    "summary": "## Summary ApostropheCMS widget styles support project-defined schema fields. If a project defines a free-form `string` style field with a CSS `property` and no selector, an editor-controlled value is rendered as an inline CSS declaration. The resulting declaration is then inserted into the widget wrapper's `style=\"...\"` attribute without HTML-attribute escaping. An attacker who can edit the widget can include a double quote in the style value, terminate the `style` attribute, and inject new HTML event-handler attributes. The payload is stored with the widget and executes in the Apostrophe site origin whenever the affected published page is rendered. This is a sibling of CVE-2026-33889 / `GHSA-97v6-998m-fp4g`. The earlier issue escaped from a `",
    "evidence": "osv:GHSA-7jg5-frgc-c67w",
    "products": [
      {
        "name": {
          "value": "apostrophe",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "4.34.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-7jg5-frgc-c67w",
      "aliases": [
        "CVE-2026-112958",
        "GHSA-7jg5-frgc-c67w"
      ],
      "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": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4.34.0"
                }
              ]
            }
          ],
          "package": {
            "name": "apostrophe",
            "purl": "pkg:npm/apostrophe",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-7jg5-frgc-c67w/GHSA-7jg5-frgc-c67w.json"
          }
        }
      ],
      "modified": "2026-10-21T17:28:19.299025109Z",
      "provider": "osv",
      "references": [
        "https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-7jg5-frgc-c67w",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-112958",
        "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/apostrophe@4.34.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-20T17:17:33Z",
        "github_reviewed_at": "2026-10-21T17:15:07Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-112958",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 397800,
  "published_at": "2026-10-21T17:15:07+00:00"
}