{"id":"CVE-2020-11083","aliases":["GHSA-w4pj-7p68-3vgv"],"url":"https://o3.security/vulnerability/CVE-2020-11083","summary":"Stored XSS in October","details":"### Impact\nA user with access to a markdown FormWidget that stores data persistently could create a stored XSS attack against themselves and any other users with access to the generated HTML from the field.\n\n### Patches\nIssue has been patched in Build 466 (v1.0.466) & RainLab.Blog v1.4.1 by restricting the ability to store JS in markdown to only users that have been explicitly granted the `backend.allow_unsafe_markdown` permission.\n\n### Workarounds\nApply https://github.com/octobercms/october/commit/9ecfb4867baae14a0d3f99f5b5c1e8a979ae8746 & https://github.com/rainlab/blog-plugin/commit/6ae19a6e16ef3ba730692bc899851342c858bb94 to your installation manually if unable to upgrade to Build 466 or v1.4.1 of RainLab.Blog (if using that plugin).\n\n### References\nReported by [Sivanesh Ashok](https://stazot.com/)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Email us at [hello@octobercms.com](mailto:hello@octobercms.com)\n\n### Threat assessment:\n<img width=\"1100\" alt=\"Screen Shot 2020-03-31 at 2 01 52 PM\" src=\"https://user-images.githubusercontent.com/7253840/78070158-8f7ef580-7358-11ea-950c-226533f6a0a3.png\">","published":"2020-07-14T21:15:10.607Z","modified":"2026-10-20T10:51:45.954904930Z","cvss":{"score":4.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N"},"epss":{"score":0.01148,"percentile":0.63908,"asOf":"2026-08-23"},"cisaKev":null,"exploitsKnown":2,"affectedPackages":[{"ecosystem":"Packagist","name":"october/backend","fixedVersion":"1.0.466"}],"fix":{"url":"https://github.com/octobercms/october/commit/9ecfb4867baae14a0d3f99f5b5c1e8a979ae8746","label":"octobercms/october@9ecfb48"},"references":[{"type":"FIX","url":"https://github.com/octobercms/october/commit/9ecfb4867baae14a0d3f99f5b5c1e8a979ae8746"},{"type":"FIX","url":"https://github.com/octobercms/october/security/advisories/GHSA-w4pj-7p68-3vgv"},{"type":"FIX","url":"https://github.com/rainlab/blog-plugin/commit/6ae19a6e16ef3ba730692bc899851342c858bb94"},{"type":"EVIDENCE","url":"http://packetstormsecurity.com/files/158730/October-CMS-Build-465-XSS-File-Read-File-Deletion-CSV-Injection.html"},{"type":"EVIDENCE","url":"http://seclists.org/fulldisclosure/2020/Aug/2"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-11083"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-20T10:51:45.954904930Z"}}