{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "winter/wn-backend-module"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.2.10"
            },
            {
              "fixed": "1.2.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-32258"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-12T14:40:38Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact                                                                                                       \n                                                                                                                   \nAuthenticated Backend Users with the `backend.manage_editor` (\"Manage editor settings\") permission can provide custom styles through **Settings \u2192 Editor Settings \u2192 Markup Styles** that are compiled through the LESS CSS parser and rendered on every backend page. Previously, the compiled output was not sanitized, which could have allowed a stored XSS attack.\n\nAlthough this is a valid security issue, it\u0027s important to note that its severity is relatively low. To exploit the vulnerability, an attacker would already need to have trusted access to the Winter CMS backend with a specific administrative permission. The Winter CMS                maintainers recommend that the `backend.manage_editor` permission only be granted to trusted administrators and developers.\n\nA related issue exists in the custom CSS field at **Settings \u2192 Customize Backend \u2192 Styles** (`backend.manage_branding` permission), which uses the same rendering mechanism and is addressed separately.\n\nAll users are advised to update to the latest version to ensure their systems remain secure.\n\n### Patches\n\nThis issue has been patched in v1.2.13. The `renderCss()` method now applies `strip_tags()` to compiled CSS output before returning it.\n\n### Workarounds\n\nApply [https://github.com/wintercms/winter/commit/d28f0b9474af79cfaa80eeb9d691f7a7c4469720](https://github.com/wintercms/winter/commit/d28f0b9474af79cfaa80eeb9d691f7a7c4469720) manually if unable to upgrade to v1.2.13.\n\n### Resources\n\n- CVE-2025-61674 (identical vulnerability in October CMS, patched in v3.7.13 and v4.0.12)",
  "id": "GHSA-vgp4-2fc4-qff2",
  "modified": "2026-08-12T14:40:38Z",
  "published": "2026-08-12T14:40:38Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/wintercms/winter/security/advisories/GHSA-vgp4-2fc4-qff2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/wintercms/winter/commit/d28f0b9474af79cfaa80eeb9d691f7a7c4469720"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/wintercms/winter"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Winter: Stored XSS through Editor Settings custom styles"
}