Bypass of fix for CVE-2020-15247, Twig sandbox escape

Impact

A bypass of CVE-2020-15247 (fixed in 1.0.469 and 1.1.0) was discovered that has the same impact as CVE-2020-15247:

An 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.

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.

Patches

Issue has been patched in Build 470 (v1.0.470) and v1.1.1.

Workarounds

Apply https://github.com/octobercms/october/commit/d34fb8ab51108495a9a651b841202d935f4e12f7 to your installation manually if unable to upgrade to Build 470 or v1.1.1.

References

Reported by ka1n4t

For more information

If you have any questions or comments about this advisory:

• Email us at [email protected]

Threat assessment:

<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”>