VYPR
High severityNVD Advisory· Published Mar 13, 2018· Updated Aug 5, 2024

CVE-2018-1000073

CVE-2018-1000073

Description

RubyGems version Ruby 2.2 series: 2.2.9 and earlier, Ruby 2.3 series: 2.3.6 and earlier, Ruby 2.4 series: 2.4.3 and earlier, Ruby 2.5 series: 2.5.0 and earlier, prior to trunk revision 62422 contains a Directory Traversal vulnerability in install_location function of package.rb that can result in path traversal when writing to a symlinked basedir outside of the root. This vulnerability appears to have been fixed in 2.7.6.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

Directory traversal in RubyGems' install_location function allows writing to arbitrary filesystem paths via a symlinked basedir outside root.

Vulnerability

CVE-2018-1000073 is a directory traversal vulnerability in the RubyGems component of Ruby. The issue resides in the install_location function of package.rb and affects Ruby 2.2.9 and earlier, 2.3.6 and earlier, 2.4.3 and earlier, and 2.5.0 and earlier, prior to trunk revision 62422 [1][2][3][4]. An attacker can craft a gem that, when installed, causes files to be written to a path outside the intended directory by leveraging a symlink in the base installation directory.

Exploitation

To exploit this vulnerability, an attacker needs to convince a user or automated system to install a malicious gem. The attack requires a symlink to be present in the gem's base installation directory (basedir) pointing to an arbitrary filesystem location. During gem installation, the install_location function follows the symlink and writes gem files to the target location specified by the symlink, bypassing path restrictions.

Impact

Successful exploitation allows an attacker to write files to arbitrary locations on the filesystem with the privileges of the Ruby process performing the installation. This can lead to overwriting critical system files, configuration files, or user data, potentially enabling privilege escalation, denial of service, or remote code execution depending on the written content and permissions.

Mitigation

This vulnerability is fixed in Ruby 2.7.6 and later versions. Red Hat has released updated packages for various Ruby versions in RHSA-2018:3731, RHSA-2018:3730, RHSA-2018:3729, and RHSA-2020:0663 [1][2][3][4]. Users should upgrade RubyGems or Ruby to a patched version and ensure they only install gems from trusted sources.

AI Insight generated on May 22, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
rubygems-updateRubyGems
< 2.7.62.7.6
org.jruby:jruby-stdlibMaven
< 9.1.16.09.1.16.0

Affected products

29

Patches

2
0b06b48ab443

Apply backported RubyGems 2.7.6 patch.

https://github.com/jruby/jrubyCharles Oliver NutterFeb 16, 2018via ghsa
7 files changed · +75 20
  • lib/ruby/stdlib/rubygems/commands/owner_command.rb+1 1 modified
    @@ -62,7 +62,7 @@ def show_owners name
         end
     
         with_response response do |resp|
    -      owners = YAML.load resp.body
    +      owners = Gem::SafeYAML.load resp.body
     
           say "Owners for gem: #{name}"
           owners.each do |owner|
    
  • lib/ruby/stdlib/rubygems/package.rb+33 4 modified
    @@ -378,7 +378,7 @@ def extract_tar_gz io, destination_dir, pattern = "*" # :nodoc:
                 File.dirname destination
               end
     
    -        FileUtils.mkdir_p mkdir, mkdir_options
    +        mkdir_p_safe mkdir, mkdir_options, destination_dir, entry.full_name
     
             open destination, 'wb' do |out|
               out.write entry.read
    @@ -416,20 +416,35 @@ def install_location filename, destination_dir # :nodoc:
         raise Gem::Package::PathError.new(filename, destination_dir) if
           filename.start_with? '/'
     
    -    destination_dir = File.realpath destination_dir if
    -      File.respond_to? :realpath
    +    destination_dir = realpath destination_dir
         destination_dir = File.expand_path destination_dir
     
         destination = File.join destination_dir, filename
         destination = File.expand_path destination
     
         raise Gem::Package::PathError.new(destination, destination_dir) unless
    -      destination.start_with? destination_dir
    +      destination.start_with? destination_dir + '/'
     
         destination.untaint
         destination
       end
     
    +  def mkdir_p_safe mkdir, mkdir_options, destination_dir, file_name
    +    destination_dir = realpath File.expand_path(destination_dir)
    +    parts = mkdir.split(File::SEPARATOR)
    +    parts.reduce do |path, basename|
    +      path = realpath path  unless path == ""
    +      path = File.expand_path(path + File::SEPARATOR + basename)
    +      lstat = File.lstat path rescue nil
    +      if !lstat || !lstat.directory?
    +        unless path.start_with? destination_dir and (FileUtils.mkdir path, mkdir_options rescue false)
    +          raise Gem::Package::PathError.new(file_name, destination_dir)
    +        end
    +      end
    +      path
    +    end
    +  end
    +
       ##
       # Loads a Gem::Specification from the TarEntry +entry+
     
    @@ -603,6 +618,10 @@ def verify_files gem
           raise Gem::Package::FormatError.new \
                   'package content (data.tar.gz) is missing', @gem
         end
    +
    +    if duplicates = @files.group_by {|f| f }.select {|k,v| v.size > 1 }.map(&:first) and duplicates.any?
    +      raise Gem::Security::Exception, "duplicate files in the package: (#{duplicates.map(&:inspect).join(', ')})"
    +    end
       end
     
       ##
    @@ -616,6 +635,16 @@ def verify_gz entry # :nodoc:
         raise Gem::Package::FormatError.new(e.message, entry.full_name)
       end
     
    +  if File.respond_to? :realpath
    +    def realpath file
    +      File.realpath file
    +    end
    +  else
    +    def realpath file
    +      file
    +    end
    +  end
    +
     end
     
     require 'rubygems/package/digest_io'
    
  • lib/ruby/stdlib/rubygems/package/tar_header.rb+14 9 modified
    @@ -104,25 +104,30 @@ def self.from(stream)
         fields = header.unpack UNPACK_FORMAT
     
         new :name     => fields.shift,
    -        :mode     => fields.shift.oct,
    -        :uid      => fields.shift.oct,
    -        :gid      => fields.shift.oct,
    -        :size     => fields.shift.oct,
    -        :mtime    => fields.shift.oct,
    -        :checksum => fields.shift.oct,
    +        :mode     => strict_oct(fields.shift),
    +        :uid      => strict_oct(fields.shift),
    +        :gid      => strict_oct(fields.shift),
    +        :size     => strict_oct(fields.shift),
    +        :mtime    => strict_oct(fields.shift),
    +        :checksum => strict_oct(fields.shift),
             :typeflag => fields.shift,
             :linkname => fields.shift,
             :magic    => fields.shift,
    -        :version  => fields.shift.oct,
    +        :version  => strict_oct(fields.shift),
             :uname    => fields.shift,
             :gname    => fields.shift,
    -        :devmajor => fields.shift.oct,
    -        :devminor => fields.shift.oct,
    +        :devmajor => strict_oct(fields.shift),
    +        :devminor => strict_oct(fields.shift),
             :prefix   => fields.shift,
     
             :empty => empty
       end
     
    +  def self.strict_oct(str)
    +    return str.oct if str =~ /\A[0-7]*\z/
    +    raise ArgumentError, "#{str.inspect} is not an octal string"
    +  end
    +
       ##
       # Creates a new TarHeader using +vals+
     
    
  • lib/ruby/stdlib/rubygems/package/tar_writer.rb+2 0 modified
    @@ -196,6 +196,8 @@ def add_file_signed name, mode, signer
           digest_name == signer.digest_name
         end
     
    +    raise "no #{signer.digest_name} in #{digests.values.compact}" unless signature_digest
    +
         if signer.key then
           signature = signer.sign signature_digest.digest
     
    
  • lib/ruby/stdlib/rubygems.rb+1 1 modified
    @@ -10,7 +10,7 @@
     require 'thread'
     
     module Gem
    -  VERSION = "2.6.14"
    +  VERSION = "2.6.14.1"
     end
     
     # Must be first since it unloads the prelude from 1.9.2
    
  • lib/ruby/stdlib/rubygems/server.rb+13 1 modified
    @@ -631,6 +631,18 @@ def root(req, res)
           executables = nil if executables.empty?
           executables.last["is_last"] = true if executables
     
    +      # Pre-process spec homepage for safety reasons
    +      begin
    +        homepage_uri = URI.parse(spec.homepage)
    +        if [URI::HTTP, URI::HTTPS].member? homepage_uri.class
    +          homepage_uri = spec.homepage
    +        else
    +          homepage_uri = "."
    +        end
    +      rescue URI::InvalidURIError
    +        homepage_uri = "."
    +      end
    +
           specs << {
             "authors"             => spec.authors.sort.join(", "),
             "date"                => spec.date.to_s,
    @@ -640,7 +652,7 @@ def root(req, res)
             "only_one_executable" => (executables && executables.size == 1),
             "full_name"           => spec.full_name,
             "has_deps"            => !deps.empty?,
    -        "homepage"            => spec.homepage,
    +        "homepage"            => homepage_uri,
             "name"                => spec.name,
             "rdoc_installed"      => Gem::RDoc.new(spec).rdoc_installed?,
             "ri_installed"        => Gem::RDoc.new(spec).ri_installed?,
    
  • lib/ruby/stdlib/rubygems/specification.rb+11 4 modified
    @@ -15,6 +15,7 @@
     require 'rubygems/stub_specification'
     require 'rubygems/util/list'
     require 'stringio'
    +require 'uri'
     
     ##
     # The Specification class contains the information for a Gem.  Typically
    @@ -2810,10 +2811,16 @@ def validate packaging = true
           raise Gem::InvalidSpecificationException, "#{lazy} is not a summary"
         end
     
    -    if homepage and not homepage.empty? and
    -       homepage !~ /\A[a-z][a-z\d+.-]*:/i then
    -      raise Gem::InvalidSpecificationException,
    -            "\"#{homepage}\" is not a URI"
    +    # Make sure a homepage is valid HTTP/HTTPS URI
    +    if homepage and not homepage.empty?
    +      begin
    +        homepage_uri = URI.parse(homepage)
    +        unless [URI::HTTP, URI::HTTPS].member? homepage_uri.class
    +          raise Gem::InvalidSpecificationException, "\"#{homepage}\" is not a valid HTTP URI"
    +        end
    +      rescue URI::InvalidURIError
    +        raise Gem::InvalidSpecificationException, "\"#{homepage}\" is not a valid HTTP URI"
    +      end
         end
     
         # Warnings
    
1b931fc03b81

Non-working patch for deducing symlinked base-dirs

https://github.com/rubygems/rubygemsJonathan ClaudiusFeb 8, 2018via ghsa
1 file changed · +2 0
  • lib/rubygems/package.rb+2 0 modified
    @@ -421,6 +421,8 @@ def install_location filename, destination_dir # :nodoc:
         destination_dir = File.expand_path destination_dir
     
         destination = File.join destination_dir, filename
    +    destination = File.realpath destination if
    +      File.respond_to? :realpath
         destination = File.expand_path destination
     
         raise Gem::Package::PathError.new(destination, destination_dir) unless
    

Vulnerability mechanics

Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

20

News mentions

0

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