The SecureRandom.random_bytes function in lib/securerandom.rb in Ruby before 1.8.7-p352 and 1.9.x before 1.9.2-p290 relies on PID values for initialization, which makes it easier for context-dependent attackers to predict the result string by leveraging knowledge of random strings obtained in an earlier process with the same PID.

Ruby before 1.8.7-p352 does not reset the random seed upon forking, which makes it easier for context-dependent attackers to predict the values of random numbers by leveraging knowledge of the number sequence obtained in a different child process, a related issue to CVE-2003-0900. NOTE: this issue exists because of a regression during Ruby 1.8.6 development.