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.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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- High
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
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.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.
- Record
CVE-2021-21264- CVSS 3.1
- 5.2 Medium
CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L - Weakness
- CWE-862
- Updated
- 2026-11-02
EUVDEUVD-2021-1058
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.
- Record
EUVD-2021-1058- CVSS 3.1
- 5.2 Medium
CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-fcr8-6q7r-m4wg
Bypass of fix for CVE-2020-26231, Twig sandbox escape
Impact
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.
Patches
Issue has been patched in Build 472 (v1.0.472) and v1.1.2.
Workarounds
Apply https://github.com/octobercms/october/commit/f63519ff1e8d375df30deba63156a2fc97aa9ee7 to your installation manually if unable to upgrade to Build 472 or v1.1.2.
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">
- Record
GHSA-fcr8-6q7r-m4wg- CVSS 3.1
- 5.2 Medium
CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L - Weakness
- CWE-862
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2021-21264- CVSS 3.1
- 5.2 Medium
CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L - CVSS 2.0
- 4.4 Medium
AV:L/AC:M/Au:N/C:P/I:P/A:P - Weakness
- CWE-862
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-21264- CVSS 3.1
- 5.2 Medium
CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L - Updated
- 2026-11-02
OSVGHSA-fcr8-6q7r-m4wg
Bypass of fix for CVE-2020-26231, Twig sandbox escape
Impact
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.
Patches
Issue has been patched in Build 472 (v1.0.472) and v1.1.2.
Workarounds
Apply https://github.com/octobercms/october/commit/f63519ff1e8d375df30deba63156a2fc97aa9ee7 to your installation manually if unable to upgrade to Build 472 or v1.1.2.
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">
- Record
GHSA-fcr8-6q7r-m4wg- CVSS 3.1
- 5.2 Medium
CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L - Weakness
- CWE-862
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
october/cmsPackagist |
1.0.471 to 1.0.471 | 1.0.472 |
october/cmsPackagist |
1.1.1 to 1.1.1 | 1.1.2 |
october/cmsPackagist |
1.0.471 up to 1.0.472, plus listed versions v1.0.471 |
1.0.472 |
october/cmsPackagist |
1.1.1 up to 1.1.2, plus listed versions v1.1.1 |
1.1.2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21264 is a medium vulnerability (CVSS 5.2) in Octobercms October, published May 3, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.26%, the 18th percentile. Fixed in october/cms 1.0.472.