Debian: CVE-2017-16654: symfony -- security update

An issue was discovered in Symfony before 2.7.38, 2.8.31, 3.2.14, 3.3.13, 3.4-BETA5, and 4.0-BETA5. The Intl component includes various bundle readers that are used to read resource bundles from the local filesystem. The read() methods of these classes use a path and a locale to determine the language bundle to retrieve. The locale argument value is commonly retrieved from untrusted user input (like a URL parameter). An attacker can use this argument to navigate to arbitrary directories via the dot-dot-slash attack, aka Directory Traversal.