A sandbox information disclosure exists in Twig before 1.38.0 and 2.x before 2.7.0 because, under some circumstances, it is possible to call the __toString() method on an object even if not allowed by the security policy in place.
https://www.debian.org/security/2019/dsa-4419
https://symfony.com/blog/twig-sandbox-information-disclosure
https://seclists.org/bugtraq/2019/Mar/60
https://github.com/twigphp/Twig/commit/eac5422956e1dcca89a3669a03a3ff32f0502077