Twig is a template language for PHP. Versions 1.x prior to 1.44.7, 2.x prior to 2.15.3, and 3.x prior to 3.4.3 encounter an issue when the filesystem loader loads templates for which the name is a user input. It is possible to use the `source` or `include` statement to read arbitrary files from outside the templates' directory when using a namespace like `@somewhere/../some.file`. In such a case, validation is bypassed. Versions 1.44.7, 2.15.3, and 3.4.3 contain a fix for validation of such template names. There are no known workarounds aside from upgrading.

Twig is an open source template language for PHP. When in a sandbox mode, the `arrow` parameter of the `sort` filter must be a closure to avoid attackers being able to run arbitrary PHP functions. In affected versions this constraint was not properly enforced and could lead to code injection of arbitrary PHP code. Patched versions now disallow calling non Closure in the `sort` filter as is the case for some other filters. Users are advised to upgrade.