CVE-2021-21264: Bypass of fix for CVE-2020-26231, Twig sandbox escape
October is a free, open-source, self-hosted CMS platform based on the Laravel PHP Framework. A 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. An authenticated backend user with the cms.managepages, cms.managelayouts, or cms.managepartials 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. This 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. Issue has been patched in Build 472 (v1.0.472) and v1.1.2. As a workaround, apply https://github.com/octobercms/october/commit/f63519ff1e8d375df30deba63156a2fc97aa9ee7 to your installation manually if unable to upgrade to Build 472 or v1.1.2.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is CVE-2021-21264?
CVE-2021-21264 refers to a vulnerability in October, a self-hosted CMS platform based on the Laravel PHP Framework, which allows an authenticated backend user to bypass certain security restrictions.
What is the impact of CVE-2021-21264?
The impact of CVE-2021-21264 is similar to that of CVE-2020-26231 and CVE-2020-15247, and it allows an authenticated backend user to bypass certain security measures.
What software versions are affected by CVE-2021-21264?
Versions up to and including 1.0.471 of October CMS are affected, as well as versions between 1.1.0 and 1.1.1.
How can I fix CVE-2021-21264?
To fix CVE-2021-21264, update October CMS to version 1.0.470/471 or 1.1.1, which include the necessary fixes.
Where can I find more information about CVE-2021-21264?
More information about CVE-2021-21264 can be found in the GitHub security advisory: [https://github.com/octobercms/october/security/advisories/GHSA-fcr8-6q7r-m4wg](https://github.com/octobercms/october/security/advisories/GHSA-fcr8-6q7r-m4wg)