It was discovered that Ruby"s REXML library did not properly restrict XML entity expansion. An attacker could use this flaw to cause a denial of service by tricking a Ruby application using REXML to read text nodes from specially-crafted XML content, which will result in REXML consuming large amounts of system memory. It was found that the RHSA-2011-0910 update did not correctly fix the CVE-2011-1005 issue, a flaw in the method for translating an exception message into a string in the Exception class. A remote attacker could use this flaw to bypass safe level 4 restrictions, allowing untrusted code to modify arbitrary, trusted strings, which safe level 4 restrictions would otherwise prevent. The safe-level feature in Ruby 1.8.6 through 1.8.6-420, 1.8.7 through 1.8.7-330, and 1.8.8dev allows context-dependent attackers to modify strings via the Exception#to_s method, as demonstrated by changing an intended pathname