GHSA-7mpf-4465-7fc2: Winter Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-7mpf-4465-7fc2",
  "modified" : "2026-08-20T18:44:41Z",
  "published" : "2026-08-20T18:44:41Z",
  "aliases" : [ ],
  "summary" : "Winter: Stored XSS through Backend List widget image columns",
  "details" : "### Impact\n\n`Backend\\Widgets\\Lists::evalImageTypeValue()` interpolated the resolved image URL into a single-quoted `src` attribute without escaping it. Where a list column of type [`image`](https://wintercms.com/docs/v1.2/docs/backend/lists#image) rendered an attacker-influenced value, that value could break out of the attribute and inject arbitrary attributes — including event handlers — into the backend list, executing in the session of whichever backend user viewed it.\n\nWinter core ships no `image` list column, so a default installation is unaffected. Exploitation requires a plugin that renders attacker-influenced values through one.\n\nThe supported [image sources](https://wintercms.com/docs/v1.2/docs/services/image-resizing#available-sources) are plugins, themes, the Media Library, the uploads directory, and `Attach\\File` models; an arbitrary external URL is not among them. `ImageResizer::filterGetUrl()` returns the value it was given when it cannot resolve an image, however, so an unsupported value reached the attribute verbatim rather than being rejected.\n\nAs with previous issues of this kind the severity is limited: an attacker must already be able to store the value, and a backend user must then open the affected list. Note that validating a stored URL was not necessarily sufficient — a payload can survive `filter_var($url, FILTER_VALIDATE_URL)`, since `/` is valid both in a URL path and after a quoted HTML attribute value.\n\n### Patches\n\n`evalImageTypeValue()` now escapes the image URL, along with the width and height taken from the column configuration, before interpolating them into the tag.\n\nThis security issue has been fixed as of **v1.2.14** (commit [`0941c9816181095fe35d58e78e6d0c4a49238967`](https://github.com/wintercms/winter/commit/0941c9816181095fe35d58e78e6d0c4a49238967)).\n\n### Workarounds\n\nApply the commit above to `modules/backend/widgets/Lists.php` manually if you are unable to upgrade to v1.2.14.\n\n### References\n\n- https://github.com/wintercms/winter/security/advisories/GHSA-43w4-4j3c-jx29\n- https://github.com/wintercms/winter/commit/0941c9816181095fe35d58e78e6d0c4a49238967\n\n\nCredit to Seungyeon Park ([@sy460129](https://github.com/sy460129)) for reporting the issue.\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n- Email us at [hello@wintercms.com](mailto:hello@wintercms.com)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "winter/wn-backend-module"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.1.0"
      }, {
        "fixed" : "1.2.14"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/wintercms/winter/security/advisories/GHSA-7mpf-4465-7fc2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/wintercms/winter/commit/0941c9816181095fe35d58e78e6d0c4a49238967"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/wintercms/winter"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/wintercms/winter/releases/tag/v1.2.14"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-20T18:44:41Z",
    "nvd_published_at" : null
  }
}