Ruby 1.9.3 before patchlevel 286 and 2.0 before revision r37068 allows context-dependent attackers to bypass safe-level restrictions and modify untainted strings via the (1) exc_to_s or (2) name_err_to_s API function, which marks the string as tainted, a different vulnerability than CVE-2012-4466.  NOTE: this issue might exist because of a CVE-2011-1005 regression.