diff --git a/.travis.yml b/.travis.yml
index 0fe2c46b0..eae1e7dee 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,6 +9,9 @@ notifications:
     on_start: false     # default: false
 rvm:
   - 2.0.0
+before_install:
+  - sudo apt-get update -qq
+  - sudo apt-get install -qq libarchive-dev
 before_script:
   - psql -c 'create database supermarket_test;' -U postgres
   - psql supermarket_test -c 'create extension pg_trgm' -U postgres
diff --git a/Gemfile b/Gemfile
index fecc8eb13..bf5020991 100644
--- a/Gemfile
+++ b/Gemfile
@@ -34,6 +34,7 @@ gem 'semverse'
 gem 'sitemap_generator'
 gem 'redis-rails'
 gem 'yajl-ruby'
+gem 'libarchive', github: 'bcobb/winebarrel-libarchive-ruby-clone', ref: 'format-security-fix'
 
 gem 'sentry-raven', '~> 0.8.0', require: false
 gem 'statsd-ruby', require: 'statsd'
diff --git a/Gemfile.lock b/Gemfile.lock
index 23491ec67..f40064f8f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,3 +1,10 @@
+GIT
+  remote: git://github.com/bcobb/winebarrel-libarchive-ruby-clone.git
+  revision: a5a748c731415cb622282350dc92c82f8de77e5d
+  ref: format-security-fix
+  specs:
+    libarchive (0.1.2)
+
 GIT
   remote: git://github.com/gofullstack/chef-legacy.git
   revision: 3a27451f99f06b93b178b10e660e0b65f4dbfa99
@@ -460,6 +467,7 @@ DEPENDENCIES
   jbuilder
   kaminari
   launchy
+  libarchive!
   license_finder
   magiconf
   mail_view
diff --git a/app/models/cookbook_upload/archive.rb b/app/models/cookbook_upload/archive.rb
new file mode 100644
index 000000000..ee12b0e7a
--- /dev/null
+++ b/app/models/cookbook_upload/archive.rb
@@ -0,0 +1,110 @@
+require 'libarchive'
+
+class CookbookUpload
+  #
+  # This class provides access to cookbook archives. In particular, it supports
+  # finding entries in the archive which have a path matching some regular
+  # expression, and it can read the contents of files given their path. These
+  # are the two primary operations required by Supermarket to locate and
+  # process metadata and README files.
+  #
+  class Archive
+    #
+    # Indicates that the uploaded archive may not be an upload, since it does
+    # not have a +path+
+    #
+    NoPath = Class.new(RuntimeError)
+
+    #
+    # Indicates that the source could not be processed
+    #
+    Error = Class.new(RuntimeError)
+
+    #
+    # Creates a new Archive
+    #
+    # @param source [File] the source archive
+    #
+    def initialize(source)
+      @source = source
+    end
+
+    #
+    # Returns the paths of entries in the archive which match the given regular expression
+    #
+    # @param pattern [Regexp]
+    #
+    # @return [Array<String>] matching paths
+    #
+    def find(pattern)
+      matches = []
+
+      each do |entry, _|
+        next unless entry.pathname.match(pattern)
+
+        matches << entry.pathname
+      end
+
+      matches
+    end
+
+    #
+    # Reads the contents of the file at the given path
+    #
+    # @param path [String]
+    #
+    # @return [String] the contents if a file exists at the given path
+    # @return [nil] if no such file exists
+    #
+    def read(path)
+      match = nil
+
+      each do |entry, archive|
+        next unless entry.pathname == path
+
+        match = archive.read_data
+
+        break
+      end
+
+      match
+    end
+
+    private
+
+    #
+    # Iterates through each entry in the source archive
+    #
+    # @raise [NoPath] if the source has no path
+    # @raise [Error] if the source is not a compatible archive
+    #
+    # @yieldparam [::Archive::Entry] entry
+    # @yieldparam [::Archive::Reader] archive
+    #
+    # @example
+    #   archive = CookbookUpload::Archive.new(tarball)
+    #   archive.each do |entry, archive|
+    #     puts "#{entry.pathname} has the following content:\n#{archive.read_data}"
+    #   end
+    #
+    def each
+      raise NoPath unless @source.respond_to?(:path)
+
+      begin
+        ::Archive.read_open_filename(@source.path) do |archive|
+          loop do
+            entry = archive.next_header
+
+            if entry
+              yield entry, archive
+            else
+              break
+            end
+          end
+        end
+      rescue ::Archive::Error => e
+        raise Error, e.message
+      end
+    end
+  end
+end
diff --git a/app/models/cookbook_upload/parameters.rb b/app/models/cookbook_upload/parameters.rb
index 98e66d49a..d986231f7 100644
--- a/app/models/cookbook_upload/parameters.rb
+++ b/app/models/cookbook_upload/parameters.rb
@@ -1,8 +1,8 @@
 require 'active_model/errors'
+require 'cookbook_upload/archive'
 require 'cookbook_upload/metadata'
 require 'cookbook_upload/readme'
 require 'json'
-require 'rubygems/package'
 require 'set'
 
 class CookbookUpload
@@ -14,20 +14,10 @@ class Parameters
     attr_reader :tarball
 
     #
-    # Indicates that the uploaded tarball has no metdata.json entry
+    # @!attribute [r] archive
+    #   @return [Archive] An interface to +tarball+
     #
-    MissingMetadata = Class.new(RuntimeError)
-
-    #
-    # Indicates that the uploaded tarball has no README entry
-    #
-    MissingReadme = Class.new(RuntimeError)
-
-    #
-    # Indicates that the uploaded tarball may not be an upload, since it does
-    # not have a +path+
-    #
-    TarballHasNoPath = Class.new(RuntimeError)
+    attr_reader :archive
 
     #
     # Creates a new set of cookbook upload parameters
@@ -43,6 +33,7 @@ class Parameters
     def initialize(params)
       @cookbook_data = params.fetch(:cookbook)
       @tarball = params.fetch(:tarball)
+      @archive = Archive.new(@tarball)
     end
 
     #
@@ -149,30 +140,30 @@ def parse_tarball_metadata(&block)
       errors = ActiveModel::Errors.new([])
 
       begin
-        raise TarballHasNoPath unless tarball.respond_to?(:path)
-
-        Zlib::GzipReader.open(tarball.path) do |gzip|
-          Gem::Package::TarReader.new(gzip) do |tar|
-            entry = tar.find do |e|
-              e.full_name.downcase.match(%r{^(\.\/)?[^\/]+\/metadata.json})
-            end
-
-            if entry
-              metadata = Metadata.new(JSON.parse(entry.read))
-            else
-              raise MissingMetadata
-            end
+        paths = archive.find(%r{\A(\.\/)?[^\/]+\/metadata\.json})
+
+        json, non_json = paths.partition do |path|
+          begin
+            JSON.parse(archive.read(path))
+          rescue JSON::ParserError
+            false
           end
         end
-      rescue JSON::ParserError
-        errors.add(:base, I18n.t('api.error_messages.metadata_not_json'))
-      rescue MissingMetadata
-        errors.add(:base, I18n.t('api.error_messages.missing_metadata'))
+
+        if json.empty?
+          if non_json.any?
+            errors.add(:base, I18n.t('api.error_messages.metadata_not_json'))
+          else
+            errors.add(:base, I18n.t('api.error_messages.missing_metadata'))
+          end
+        else
+          metadata = Metadata.new(JSON.parse(archive.read(json.first)))
+        end
       rescue Virtus::CoercionError
         errors.add(:base, I18n.t('api.error_messages.invalid_metadata'))
-      rescue Zlib::GzipFile::Error
-        errors.add(:base, I18n.t('api.error_messages.tarball_not_gzipped'))
-      rescue TarballHasNoPath
+      rescue Archive::Error
+        errors.add(:base, I18n.t('api.error_messages.tarball_not_archive'))
+      rescue Archive::NoPath
         errors.add(:base, I18n.t('api.error_messages.tarball_has_no_path'))
       end
 
@@ -187,34 +178,24 @@ def parse_tarball_metadata(&block)
     # @yieldparam metadata [Readme] the cookbook's README
     #
     def extract_tarball_readme(&block)
+      cookbook = metadata.name
       readme = nil
-      effective_cookbook_name = metadata.name.downcase
       errors = ActiveModel::Errors.new([])
 
       begin
-        raise TarballHasNoPath unless tarball.respond_to?(:path)
-
-        Zlib::GzipReader.open(tarball.path) do |gzip|
-          Gem::Package::TarReader.new(gzip) do |tar|
-            entry = tar.find do |e|
-              e.full_name.downcase.include?("#{effective_cookbook_name}/readme")
-            end
-
-            if entry
-              extension = entry.header.name.split('.').last.strip
-              contents = entry.read
-
-              readme = Readme.new(contents: contents, extension: extension)
-            else
-              raise MissingReadme
-            end
-          end
+        path = archive.find(%r{\A(\.\/)?#{cookbook}\/readme(\.\w+)?\Z}i).first
+
+        if path
+          readme = Readme.new(
+            contents: archive.read(path),
+            extension: path.split('.').last.strip
+          )
+        else
+          errors.add(:base, I18n.t('api.error_messages.missing_readme'))
         end
-      rescue MissingReadme
-        errors.add(:base, I18n.t('api.error_messages.missing_readme'))
-      rescue Zlib::GzipFile::Error
-        errors.add(:base, I18n.t('api.error_messages.tarball_not_gzipped'))
-      rescue TarballHasNoPath
+      rescue Archive::Error
+        errors.add(:base, I18n.t('api.error_messages.tarball_not_archive'))
+      rescue Archive::NoPath
         errors.add(:base, I18n.t('api.error_messages.tarball_has_no_path'))
       end
 
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 0605b8768..ddea09359 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -40,7 +40,7 @@ en:
       missing_tarball: "Mulipart POST must include a part named 'tarball'"
       tarball_has_no_path: "Multipart POST part 'tarball' must be a file"
       non_existent_category: "Category '%{category_name}' does not exist"
-      tarball_not_gzipped: "Multipart POST part 'tarball' must be GZipped"
+      tarball_not_archive: "Multipart POST part 'tarball' must be a file archive"
       missing_metadata: "Multipart POST part 'tarball' must contain a metadata.json entry"
       missing_readme: "Multipart POST part 'tarball' must contain a README"
       metadata_not_json: "Tarball entry named 'metadata.json' could not be parsed as JSON"
diff --git a/spec/models/cookbook_upload/parameters_spec.rb b/spec/models/cookbook_upload/parameters_spec.rb
index e2bd3f4ad..942c0f5f9 100644
--- a/spec/models/cookbook_upload/parameters_spec.rb
+++ b/spec/models/cookbook_upload/parameters_spec.rb
@@ -60,6 +60,26 @@ def params(hash)
       expect(params.metadata.name).to eql('multiple')
     end
 
+    it 'is not extracted from metadata.json~' do
+      tarball = Tempfile.new('weird-metadata', 'tmp').tap do |file|
+        io = AndFeathers.build('weird-metadata') do |base|
+          base.file('metadata.json') do
+            JSON.dump(name: 'correct')
+          end
+          base.file('metadata.json~') do
+            'this is not json'
+          end
+        end.to_io(AndFeathers::GzippedTarball, :reverse_each)
+
+        file.write(io.read)
+        file.rewind
+      end
+
+      params = params(cookbook: '{}', tarball: tarball)
+
+      expect(params.metadata.name).to eql('correct')
+    end
+
     it 'is blank if the tarball parameter is not a file' do
       params = params(cookbook: '{}', tarball: 'tarball!')
 
diff --git a/spec/models/cookbook_upload_spec.rb b/spec/models/cookbook_upload_spec.rb
index 82bdcc283..e03d2f33f 100644
--- a/spec/models/cookbook_upload_spec.rb
+++ b/spec/models/cookbook_upload_spec.rb
@@ -99,14 +99,14 @@
         to include(I18n.t('api.error_messages.tarball_has_no_path'))
     end
 
-    it 'yields an error if the tarball is not GZipped' do
-      tarball = File.open('spec/support/cookbook_fixtures/not-actually-gzipped.tgz')
+    it 'yields an error if the tarball is not an archive' do
+      tarball = File.open('spec/support/cookbook_fixtures/not-an-archive.tgz')
 
       upload = CookbookUpload.new(user, cookbook: '{}', tarball: tarball)
       errors = upload.finish { |e, _| e }
 
       expect(errors.full_messages).
-        to include(I18n.t('api.error_messages.tarball_not_gzipped'))
+        to include(I18n.t('api.error_messages.tarball_not_archive'))
     end
 
     it 'yields an error if the tarball has no metadata.json entry' do
diff --git a/spec/support/cookbook_fixtures/not-actually-gzipped.tgz b/spec/support/cookbook_fixtures/not-actually-gzipped.tgz
deleted file mode 100644
index 164ea5b66..000000000
Binary files a/spec/support/cookbook_fixtures/not-actually-gzipped.tgz and /dev/null differ
diff --git a/spec/support/cookbook_fixtures/not-an-archive.tgz b/spec/support/cookbook_fixtures/not-an-archive.tgz
new file mode 100644
index 000000000..e965047ad
--- /dev/null
+++ b/spec/support/cookbook_fixtures/not-an-archive.tgz
@@ -0,0 +1 @@
+Hello