[HIGH] Fix for arbitrary command execution in custom layout update through blocks

PKSA-mt33-5d4f-b3f9 CVE-2021-39217 GHSA-c9q3-r4rv-mjm7

Affected package: openmage/magento-lts

Affected version: >=20.0.0,<20.0.19|<19.4.22

Reported by:
GitHub