Package Instance

Twig has unguarded calls to `__toString()` when nesting an object into an array
### Description

In a sandbox, an attacker can call `__toString()` on an object even if the `__toString()` method is not allowed by the security policy when the object is part of an array or an argument list (arguments to a function or a filter for instance).

### Resolution

The sandbox mode now checks the `__toString()` method call on all objects.

The patch for this issue is available [here](https://github.com/twigphp/Twig/commit/cafc608ece310e62a35a76f17e25c04ab9ed05cc) for the 3.11.x branch, and [here](https://github.com/twigphp/Twig/commit/d4a302681bca9f7c6ce2835470d53609cdf3e23e) for the 3.x branch.

### Credits

We would like to thank Jamie Schouten for reporting the issue and Fabien Potencier for providing the fix.

Twig has unguarded calls to `__isset()` and to array-accesses when the sandbox is enabled
### Description

In a sandbox, and attacker can access attributes of Array-like objects as they were not checked by the security policy.
They are now checked via the property policy and the `__isset()` method is now called after the security check.
**This is a BC break.**

### Resolution

The sandbox mode now ensures access to array-like's properties is allowed.

The patch for this issue is available [here](https://github.com/twigphp/Twig/commit/ec39a9dccc5fb4eaaba55e5d79a6f84a8dd8b69d) for the 3.11.x branch, and [here](https://github.com/twigphp/Twig/commit/b957e5a44cc0075d04ccff52f8fa9d8e6db3e3a0) for the 3.x branch.

### Credits

We would like to thank Jamie Schouten for reporting the issue and Nicolas Grekas for providing the fix.

Twig has a possible sandbox bypass
### Description

Under some circumstances, the sandbox security checks are not run which allows user-contributed templates to bypass the sandbox restrictions.

The security issue happens when all these conditions are met:

 * The sandbox is disabled globally;
 * The sandbox is enabled via a sandboxed `include()` function which references a template name (like `included.twig`) and not a `Template` or `TemplateWrapper` instance;
 * The included template has been loaded before the `include()` call but in a non-sandbox context (possible as the sandbox has been globally disabled).

### Resolution

The patch ensures that the sandbox security checks are always run at runtime.

### Credits

We would like to thank Fabien Potencier for reporting and fixing the issue.