{"id":"GHSA-fcr8-6q7r-m4wg","aliases":["CVE-2021-21264"],"title":"Bypass of fix for CVE-2020-26231, Twig sandbox escape","description":"### Impact\nA bypass of CVE-2020-26231 (fixed in 1.0.470/471 and 1.1.1) was discovered that has the same impact as CVE-2020-26231 & CVE-2020-15247:\n\nAn authenticated backend user with the `cms.manage_pages`, `cms.manage_layouts`, or `cms.manage_partials` permissions who would **normally** not be permitted to provide PHP code to be executed by the CMS due to `cms.enableSafeMode` being enabled is able to write specific Twig code to escape the Twig sandbox and execute arbitrary PHP.\n\nThis is not a problem for anyone that trusts their users with those permissions to normally write & manage PHP within the CMS by not having `cms.enableSafeMode` enabled, but would be a problem for anyone relying on `cms.enableSafeMode` to ensure that users with those permissions in production do not have access to write & execute arbitrary PHP.\n\n### Patches\nIssue has been patched in Build 472 (v1.0.472) and v1.1.2.\n\n### Workarounds\nApply https://github.com/octobercms/october/commit/f63519ff1e8d375df30deba63156a2fc97aa9ee7 to your installation manually if unable to upgrade to Build 472 or v1.1.2.\n\n### References\nReported by [ka1n4t](https://github.com/ka1n4t)\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=\"1108\" alt=\"Screen Shot 2020-10-10 at 1 21 13 PM\" src=\"https://user-images.githubusercontent.com/7253840/95663316-7de28b80-0afb-11eb-999d-a6526cf78709.png\">","severity":"medium","score":5.2,"published":"2021-05-04T17:42:33.000Z","modified":"2026-07-08T06:30:01.387Z","withdrawn":false,"knownExploited":false,"affected":[{"ecosystem":"Packagist","name":"october/cms","ranges":[{"events":[{"introduced":"1.0.471"},{"fixed":"1.0.472"}],"type":"ECOSYSTEM"}],"versions":["1.0.471","v1.0.471"],"fixed":["1.0.472"]},{"ecosystem":"Packagist","name":"october/cms","ranges":[{"events":[{"introduced":"1.1.1"},{"fixed":"1.1.2"}],"type":"ECOSYSTEM"}],"versions":["1.1.1","v1.1.1"],"fixed":["1.1.2"]}],"references":["https://github.com/octobercms/october/security/advisories/GHSA-fcr8-6q7r-m4wg","https://nvd.nist.gov/vuln/detail/CVE-2021-21264","https://github.com/octobercms/october"],"sources":[{"name":"OSV","id":"GHSA-fcr8-6q7r-m4wg","modified":"2026-07-08T06:30:01.387714458Z","url":"https://osv.dev/vulnerability/GHSA-fcr8-6q7r-m4wg"}],"assessments":[{"source":"OSV","vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L","score":5.2}]}