Carefully crafted input can cause Content-Disposition header parsing in Rack to take an unexpected amount of time, possibly resulting in a denial of service attack vector. This header is used typically used in multipart parsing. Any applications that parse multipart posts using Rack (virtually all Rails applications) are impacted.

A flaw was found in rubygem-rack in versions prior to 1.6.12 and 2.0.8. An information leak may allow an attacker to find and hijack sessions using timing attacks targeting the session ID. The highest threat from the vulnerability is to data confidentiality.