Heap-based buffer overflow in the rbstrjustify function in string.c in Ruby 1.9.1 before 1.9.1-p376 allows context-dependent attackers to execute arbitrary code via unspecified vectors involving (1) String#ljust, (2) String#center, or (3) String#rjust. NOTE: some of these details are obtained from third party information.

Buffer overflow in Ruby 1.9.x before 1.9.1-p429 on Windows might allow local users to gain privileges via a crafted ARGF.inplacemode value that is not properly handled when constructing the filenames of the backup files.

The SecureRandom.randombytes 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.

Drew Yao of Apple Product Security reported a flaw in how Ruby's BigDecimal implementation. In a 64-bit program, if the amount of memory to allocate is greater than 2^32, the allocated amount will be truncated to a 32-bit unsigned integer, however the amount to memset will use the full 64-bit number, leading to a crash or memory corruption. After the memset, the unexpectedly small buffer could be used in other ways that lead to memory corruption or, possibly, code execution.

This flaw only affects 64-bit processes.

To test whether or not ruby is vulnerable, the following can be used (on a vulnerable ruby it will cause a segfault):

$ ruby -e 'require "bigdecimal"; BigDecimal.new("8").(0x20000000)'

Upstream committed the following to fix the flaw:

http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/trunk/ext/bigdecimal/bigdecimal.c?r1=29364&r2=30993