ASA-2019-00361 – RubyGems: Installing a malicious gem may lead to arbitrary code execution

An issue was discovered in RubyGems 2.6 and later through 3.0.2. A crafted gem with a multi-line name is not handled correctly. Therefore, an attacker could inject arbitrary code to the stub line of gemspec, which is eval-ed by code in ensure_loadable_spec during the preinstall check.

ASA-2019-00360 – RubyGems: Escape sequence injection vulnerability in API response handling

An issue was discovered in RubyGems 2.6 and later through 3.0.2. Gem::GemcutterUtilities#with_response may output the API response to stdout as it is. Therefore, if the API side modifies the response, escape sequence injection may occur.

ASA-2019-00357 – RubyGems: Delete directory using symlink when decompressing tar

A directory traversal issue was discovered in RubyGems 2.7.6 and later through 3.0.2. Before making new directories or touching files (which now include path-checking code for symlinks), it would delete the target destination. If that destination was hidden behind a symlink, a malicious gem could delete arbitrary files on the user’s machine, presuming the attacker could guess at paths. Given how frequently gem is run as sudo, and how predictable paths are on modern systems (/tmp,/usr, etc.), this could likely lead to data loss or an unusable system.