The Zip::File component in the rubyzip gem before 1.2.1 for Ruby has a directory traversal vulnerability. If a site allows uploading of .zip files, an attacker can upload a malicious file that uses "../" pathname substrings to write arbitrary files to the filesystem.
https://github.com/rubyzip/rubyzip/releases
https://github.com/rubyzip/rubyzip/issues/315