Auth bypass in Octobercms October

CVE-2021-21264

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.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. 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.

Vulnerability class: Broken Access Control

EPSS: 0.003 (18.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.2 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2021-21264?
CVE-2021-21264 is a medium-severity vulnerability in Octobercms October, classified under Missing Authorization. CVSS score: 5.2/10. Published 2021-05-03.
How severe is CVE-2021-21264?
Medium severity. CVSS v3 base score is 5.2 out of 10.
Is CVE-2021-21264 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.