The JSON gem before 1.5.5, 1.6.x before 1.6.8, and 1.7.x before 1.7.7 for Ruby allows remote attackers to cause a denial of service (resource consumption) or bypass the mass assignment protection mechanism via a crafted JSON document that triggers the creation of arbitrary Ruby symbols or certain internal objects, as demonstrated by conducting a SQL injection attack against Ruby on Rails, aka "Unsafe Object Creation Vulnerability."
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.