{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.7.12"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "october/system"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.7.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.0.11"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "october/system"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.0.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-61676"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-09T20:12:24Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "A cross-site scripting (XSS) vulnerabilities was identified in October CMS backend configuration forms:\n\n- **Branding and Appearances Styles**  \n   A user with the `Customize Backend Styles` permission could inject malicious HTML/JS into the stylesheet input at  \n   *Settings \u2192 Branding \u0026 Appearance \u2192 Styles*.  \n\nA specially crafted input could break out of the intended `\u003cstyle\u003e` context, allowing arbitrary script execution across backend pages for all users.\n\n---\n\n### Impact\n- Persistent XSS across the backend interface.  \n- Exploitable by lower-privileged accounts with the above permissions.  \n- Potential consequences include privilege escalation, session hijacking, and execution of unauthorized actions in victim sessions.\n\n---\n\n### Patches\nThe vulnerability has been patched in **v4.0.12** and **v3.7.13**.  \nStylesheet inputs are now sanitized to prevent injection of arbitrary HTML/JS.  \n\nAll users are strongly encouraged to upgrade to the latest patched version.\n\n---\n\n### Workarounds\nIf upgrading immediately is not possible:  \n- Restrict the permissions `Customize Backend Styles` to fully trusted administrators only.  \n\nThis reduces exposure but does not fully eliminate risk.\n\n---\n\n### Credits\n- Reported by **[Nakkouch Tarek](https://github.com/nakkouchtarek)**",
  "id": "GHSA-wvpq-h33f-8rp6",
  "modified": "2026-01-09T20:12:24Z",
  "published": "2026-01-09T20:12:24Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/octobercms/october/security/advisories/GHSA-wvpq-h33f-8rp6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/octobercms/october"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "October CMS Vulnerable to Stored XSS via Branding Styles"
}