diff --git a/check_latest_errata.rb b/check_latest_errata.rb
new file mode 100755
index 0000000..769ee81
--- /dev/null
+++ b/check_latest_errata.rb
@@ -0,0 +1,140 @@
+#!/usr/bin/env ruby
+
+# frozen_string_literal: true
+
+require 'optparse'
+require_relative 'lib/deb_erratum_rss'
+require_relative 'lib/errata_statistics'
+
+# get Ubuntu-ESM errata for specific releases from USN-API instead of RSS-feed,
+# because RSS-feed probably does not hold latest errata for Ubuntu-ESM releases
+USE_USN_API = true
+
+search_num = 5
+warn_num = 3
+crit_num = 1
+@debug = false
+@res = {}
+@perf_data = []
+@long_text = []
+
+def eval_result(id, found, searched, warn, crit)
+  @res[id] = case found.length
+             when (crit + 1)..warn then :warning
+             when 0..crit then :critical
+             end
+
+  # see https://nagios-plugins.org/doc/guidelines.html#AEN200
+  @perf_data << "'#{id}'=#{found.length};#{warn};#{crit};0;#{searched.length}"
+
+  @long_text << if found.length == searched.length
+                  "#{id} errata up-to-date"
+                else
+                  "#{id} errata miss #{(found - searched).join(', ')}"
+                end
+end
+
+optparse = OptionParser.new do |opts|
+  opts.banner = 'Usage: check_latest_errata.rb [options] <path>'
+
+  opts.on('-q', '--query-num NUM', Integer, "Number of errata that should be queried (default: #{search_num})") do |v|
+    search_num = v
+  end
+  opts.on('-w', '--warn NUM', Integer, "Threshold for warning (default: #{warn_num})") do |v|
+    raise 'warning threshold must be positive' if v.negative?
+
+    warn_num = v
+  end
+  opts.on('-c', '--crit NUM', Integer, "Threshold for critical (default: #{crit_num})") do |v|
+    raise 'critical threshold must be positive' if v.negative?
+
+    crit_num = v
+  end
+  opts.on('-d', '--[no-]debug', 'Debug output for testing') do |v|
+    @debug = v
+  end
+end
+optparse.parse!
+
+path = ARGV.pop
+unless path
+  warn optparse
+  exit 3
+end
+
+raise 'critical threshold must be smaller than query-num' if crit_num > search_num
+raise 'warning threshold must be smaller than query-num' if warn_num > search_num
+raise 'critical threshold must be smaller than warning threshold' if crit_num > warn_num
+raise 'errata file path is not a directory' unless File.directory? path
+
+begin
+  # Debian
+  dsa = LatestDsaErratum.new
+  dla = LatestDlaErratum.new
+  warn "Latest DLA Erratum #{dla.latest_id} (#{dla.latest_published})" if @debug
+  warn "Latest DSA Erratum #{dsa.latest_id} (#{dsa.latest_published})" if @debug
+  deb_stats = ErrataStatistics.new File.join(path, 'debian_errata.json')
+  search_ids = dla.recent(search_num).errata_ids
+  search_ids += dsa.recent(search_num).errata_ids
+  found = deb_stats.search_for_name(search_ids).map { |x| x['name'] }
+  warn "Searched for #{search_ids}\nFound #{found.inspect}" if @debug
+  eval_result('debian', found, search_ids, warn_num * 2, crit_num * 2)
+
+  # Ubuntu
+  usn = LatestUsnErratum.new
+  warn "Latest USN Erratum #{usn.latest_id} (#{usn.latest_published})" if @debug
+  stats = ErrataStatistics.new File.join(path, 'ubuntu_errata.json')
+  search_ids = usn.recent(search_num).errata_ids
+  warn "Search for #{search_ids}" if @debug
+  found = stats.search_for_name(search_ids).map { |x| x['name'] }
+  warn "Found #{found.inspect}" if @debug
+  eval_result('ubuntu', found, search_ids, warn_num, crit_num)
+
+  # Ubuntu-ESM
+  search_ids = if USE_USN_API
+                 require_relative 'lib/ubuntu_security_api'
+                 esm_releases = [
+                   'xenial',
+                   'bionic'
+                 ]
+                 usa = UbuntuSecurityApi.new(retry: 3)
+                 esm_releases.map do |rel|
+                   usa.latest_errata(rel, search_num).map { |notice| notice['id'] }
+                 end.flatten.uniq
+               else
+                 usn = LatestUsnErratum.new
+                 warn "Latest USN Erratum #{usn.latest_id} (#{usn.latest_published})" if @debug
+                 usn.recent(search_num * 2).errata_ids
+               end
+  stats = ErrataStatistics.new File.join(path, 'ubuntu-esm_errata.json')
+  # Look for the doubled amount since it is less likely that USNs are found for ESM releases
+  warn "Search for #{search_ids}" if @debug
+  found = stats.search_for_name(search_ids).map { |x| x['name'] }
+  warn "Found #{found.map { |e| e['name'] }.inspect}" if @debug
+  factor = search_ids.length / search_num
+  eval_result('ubuntu-esm', found, search_ids, warn_num * factor, crit_num * factor)
+
+  out = StringIO.new
+  out << 'ERRATA '
+  critical = @res.map { |_k, v| v == :critical }.first
+  warning = @res.map { |_k, v| v == :warning }.first
+  out << if critical
+           "CRIT #{critical} misses errata"
+         elsif warning
+           "WARN #{warning} misses errata"
+         else
+           'OK'
+         end
+  out << '; |' << @perf_data.shift << "\n"
+  out << @long_text.join(";\n")
+  out << '; | '
+  out << @perf_data.join("\n")
+
+  puts out.string
+rescue StandardErrror => e
+  puts "ERRATA EXCEPTION #{e}"
+  exit 3
+end
+
+exit 2 if @res.values.include? :critical
+exit 1 if @res.values.include? :warning