Various methods in WEBrick::HTTPRequest in Ruby 1.9.2 and 1.8.7 and earlier do not validate the X-Forwarded-For, X-Forwarded-Host and X-Forwarded-Server headers in requests, which might allow remote attackers to inject arbitrary text into log files or bypass intended address parsing via a crafted header.

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.

A race condition was found in the way the secure implementation of Ruby fileutils' remove system entries method (removeentrysecure()), removed directory trees. A local attacker could use this flaw to conduct symbolic link attacks, leading to removal of arbitrary files or directories on the system.

References: [1] http://www.ruby-lang.org/en/news/2011/02/18/fileutils-is-vulnerable-to-symlink-race-attacks/

Upstream patch (against trunk): [2] http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=30896

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

Ruby (aka CRuby) 1.9 before 1.9.3-p327 and 2.0 before r37575 computes hash values without properly restricting the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted input to an application that maintains a hash table, as demonstrated by a universal multicollision attack against a variant of the MurmurHash2 algorithm, a different vulnerability than CVE-2011-4815.

Algorithmic complexity vulnerability in Gem::Version::ANCHOREDVERSIONPATTERN in lib/rubygems/version.rb in RubyGems before 1.8.23.2, 1.8.24 through 1.8.26, 2.0.x before 2.0.10, and 2.1.x before 2.1.5, as used in Ruby 1.9.0 through 2.0.0p247, allows remote attackers to cause a denial of service (CPU consumption) via a crafted gem version that triggers a large amount of backtracking in a regular expression. NOTE: this issue is due to an incomplete fix for CVE-2013-4287.

Algorithmic complexity vulnerability in Gem::Version::VERSIONPATTERN in lib/rubygems/version.rb in RubyGems before 1.8.23.1, 1.8.24 through 1.8.25, 2.0.x before 2.0.8, and 2.1.x before 2.1.0, as used in Ruby 1.9.0 through 2.0.0p247, allows remote attackers to cause a denial of service (CPU consumption) via a crafted gem version that triggers a large amount of backtracking in a regular expression.

(1) DL and (2) Fiddle in Ruby 1.9 before 1.9.3 patchlevel 426, and 2.0 before 2.0.0 patchlevel 195, do not perform taint checking for native functions, which allows context-dependent attackers to bypass intended $SAFE level restrictions.

An unrestricted entity expansion flaw was reported in Ruby that can lead to a denial of service in REXML. When reading text nodes from an XML document, the REXML parser could be coerced into allocating extremely large string objects which could consume all available memory on the system.

Impacted code would look similar to the following:

document = REXML::Document.new somexmldoc document.root.text

In this case, when the 'text' method is called, entities will be expanded. An attacker could send a relatively small XML document that, when the entities were resolved, would consume extremely large amounts of memory on the target system. It is noted that this vulnerability is similar to the 'Billion Laughs' attack, and is also related to CVE-2013-1664 (Python).

The upstream advisory has a work-around patch that limits the size of entity substitutions.

External References:

http://www.ruby-lang.org/en/news/2013/02/22/rexml-dos-2013-02-22/

Puppet 2.7.x before 2.7.21 and 3.1.x before 3.1.1, when running Ruby 1.9.3 or later, allows remote attackers to execute arbitrary code via vectors related to "serialized attributes."

A cross-site scripting (XSS) flaw was found in the way Darkfish Rdoc HTML generator / template of RDoc, HTML and command-line documentation producing tool for Ruby, performed sanitization of certain values when creating Rdoc documentation. When Ruby on Rails application exposed its documentation via network, a remote attacker could provide a specially-crafted URL that, when opened would lead to arbitrary web script or HTML code execution in the context of (particular Ruby on Rails application) user's session.

This issue affects RDoc versions 2.3.0 to 3.12.

The URI.decodewwwformcomponent method in Ruby before 1.9.2-p330 allows remote attackers to cause a denial of service (catastrophic regular expression backtracking, resource consumption, or application crash) via a crafted string.

RubyGems 2.0.x before 2.0.16, 2.2.x before 2.2.4, and 2.4.x before 2.4.7 does not validate the hostname when fetching gems or making API requests, which allows remote attackers to redirect requests to arbitrary domains via a crafted DNS SRV record, aka a "DNS hijack attack."