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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.2 · CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L

EPSS

• CVE-2020-26231: 0.29% estimated exploitation activity in the next 30 days; percentile 21.96 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.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. 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…

Published by the source

23 Nov 2020, 20:54 UTC

Last modified by the source

9 Jan 2023, 05:04 UTC

Source last checked

26 Oct 2026, 13:56 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-r89v-cgv7-3jhx

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# Patch Next advisory brief: CVE-2020-26231

Advisory: Bypass of fix for CVE-2020-15247, Twig sandbox escape
IDs: CVE-2020-26231, GHSA-r89v-cgv7-3jhx
Record: https://patchnext.com/advisories/cve-2020-26231 (revision 1, source checked 26 Oct 2026, 13:56 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: october/cms 1.0.470. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist october/cms: affected >= 1.0.469, <= 1.0.469; fixed in 1.0.470

## Suggested inspection (read-only)
- Packagist october/cms: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on october/cms.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-r89v-cgv7-3jhx (GitHub-reviewed advisory GHSA-r89v-cgv7-3jhx lists affected ranges: Packagist october/cms >=1.0.469 <=1.0.469)

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