diff --git a/lib/bundler/bundler.gemspec b/lib/bundler/bundler.gemspec
index bd48d810286825..e6d77310c670f3 100644
--- a/lib/bundler/bundler.gemspec
+++ b/lib/bundler/bundler.gemspec
@@ -36,9 +36,11 @@ Gem::Specification.new do |s|
 
   s.files = Dir.glob("lib/bundler{.rb,/**/*}", File::FNM_DOTMATCH).reject {|f| File.directory?(f) }
 
-  # Bundler reuses RubyGems' vendored URI. Ship a copy under lib/rubygems so
-  # Bundler stays self-contained on RubyGems versions that predate it.
+  # Bundler reuses RubyGems' vendored URI and SecureRandom. Ship a copy under
+  # lib/rubygems so Bundler stays self-contained on RubyGems versions that
+  # predate them.
   s.files += Dir.glob("lib/rubygems/vendor/uri/**/*", File::FNM_DOTMATCH).reject {|f| File.directory?(f) }
+  s.files += Dir.glob("lib/rubygems/vendor/securerandom/**/*", File::FNM_DOTMATCH).reject {|f| File.directory?(f) }
 
   # include the gemspec itself because warbler breaks w/o it
   s.files += %w[lib/bundler/bundler.gemspec]
diff --git a/lib/bundler/vendor/securerandom/lib/securerandom.rb b/lib/bundler/vendor/securerandom/lib/securerandom.rb
deleted file mode 100644
index 01b7fa15a6fe6f..00000000000000
--- a/lib/bundler/vendor/securerandom/lib/securerandom.rb
+++ /dev/null
@@ -1,102 +0,0 @@
-# -*- coding: us-ascii -*-
-# frozen_string_literal: true
-
-require 'random/formatter'
-
-# == Secure random number generator interface.
-#
-# This library is an interface to secure random number generators which are
-# suitable for generating session keys in HTTP cookies, etc.
-#
-# You can use this library in your application by requiring it:
-#
-#   require 'bundler/vendor/securerandom/lib/securerandom'
-#
-# It supports the following secure random number generators:
-#
-# * openssl
-# * /dev/urandom
-# * Win32
-#
-# Bundler::SecureRandom is extended by the Random::Formatter module which
-# defines the following methods:
-#
-# * alphanumeric
-# * base64
-# * choose
-# * gen_random
-# * hex
-# * rand
-# * random_bytes
-# * random_number
-# * urlsafe_base64
-# * uuid
-#
-# These methods are usable as class methods of Bundler::SecureRandom such as
-# +Bundler::SecureRandom.hex+.
-#
-# If a secure random number generator is not available,
-# +NotImplementedError+ is raised.
-
-module Bundler::SecureRandom
-
-  # The version
-  VERSION = "0.4.1"
-
-  class << self
-    # Returns a random binary string containing +size+ bytes.
-    #
-    # See Random.bytes
-    def bytes(n)
-      return gen_random(n)
-    end
-
-    # Compatibility methods for Ruby 3.2, we can remove this after dropping to support Ruby 3.2
-    def alphanumeric(n = nil, chars: ALPHANUMERIC)
-      n = 16 if n.nil?
-      choose(chars, n)
-    end if RUBY_VERSION < '3.3'
-
-    private
-
-    # :stopdoc:
-
-    # Implementation using OpenSSL
-    def gen_random_openssl(n)
-      return OpenSSL::Random.random_bytes(n)
-    end
-
-    # Implementation using system random device
-    def gen_random_urandom(n)
-      ret = Random.urandom(n)
-      unless ret
-        raise NotImplementedError, "No random device"
-      end
-      unless ret.length == n
-        raise NotImplementedError, "Unexpected partial read from random device: only #{ret.length} for #{n} bytes"
-      end
-      ret
-    end
-
-    begin
-      # Check if Random.urandom is available
-      Random.urandom(1)
-      alias gen_random gen_random_urandom
-    rescue RuntimeError
-      begin
-        require 'openssl'
-      rescue NoMethodError
-        raise NotImplementedError, "No random device"
-      else
-        alias gen_random gen_random_openssl
-      end
-    end
-
-    # :startdoc:
-
-    # Generate random data bytes for Random::Formatter
-    public :gen_random
-  end
-end
-
-Bundler::SecureRandom.extend(Random::Formatter)
diff --git a/lib/bundler/vendored_securerandom.rb b/lib/bundler/vendored_securerandom.rb
index 6a704dbd40e487..2a4fd52f1e2efa 100644
--- a/lib/bundler/vendored_securerandom.rb
+++ b/lib/bundler/vendored_securerandom.rb
@@ -1,12 +1,15 @@
 # frozen_string_literal: true
 
-# Use RubyGems vendored copy when available. Otherwise fallback to Bundler
-# vendored copy. The vendored copy in Bundler can be removed once support for
-# RubyGems 3.5.18 is dropped.
+# Reuse RubyGems' vendored SecureRandom (Gem::SecureRandom). The Bundler gem
+# ships a copy under lib/rubygems/vendor, so this resolves even on RubyGems
+# versions that predate it. Fall back to the stdlib only when no vendored copy
+# is available at all.
 
-begin
-  require "rubygems/vendored_securerandom"
-rescue LoadError
-  require_relative "vendor/securerandom/lib/securerandom"
-  Gem::SecureRandom = Bundler::SecureRandom
+unless defined?(Gem::SecureRandom)
+  begin
+    require "rubygems/vendor/securerandom/lib/securerandom"
+  rescue LoadError
+    require "securerandom"
+    Gem::SecureRandom = SecureRandom
+  end
 end
diff --git a/lib/rubygems/vendor/securerandom/lib/securerandom.rb b/lib/rubygems/vendor/securerandom/lib/securerandom.rb
index b6f1d71ad39408..dd759fedaa563e 100644
--- a/lib/rubygems/vendor/securerandom/lib/securerandom.rb
+++ b/lib/rubygems/vendor/securerandom/lib/securerandom.rb
@@ -38,6 +38,10 @@
 # If a secure random number generator is not available,
 # +NotImplementedError+ is raised.
 
+# Skip reloading when an identical copy (e.g. the one shipped inside the Bundler
+# gem) was already required from a different path, to avoid redefinition warnings.
+return if defined?(Gem::SecureRandom::VERSION)
+
 module Gem::SecureRandom
 
   # The version
diff --git a/spec/bundler/bundler/friendly_errors_spec.rb b/spec/bundler/bundler/friendly_errors_spec.rb
index 426e3c856d8fb5..3d6cabdf11ebcb 100644
--- a/spec/bundler/bundler/friendly_errors_spec.rb
+++ b/spec/bundler/bundler/friendly_errors_spec.rb
@@ -133,11 +133,9 @@
 
     context "Java::JavaLang::OutOfMemoryError", :jruby_only do
       it "Bundler.ui receive error" do
-        install_gemfile <<-G, raise_on_error: false, env: { "JRUBY_OPTS" => "-J-Xmx32M" }, artifice: nil
-          source "https://gem.repo1"
-        G
-
-        expect(err).to include("JVM has run out of memory")
+        error = Java::JavaLang::OutOfMemoryError.new
+        expect(Bundler.ui).to receive(:error).with(/JVM has run out of memory/)
+        Bundler::FriendlyErrors.log_error(error)
       end
     end
 
diff --git a/spec/bundler/support/path.rb b/spec/bundler/support/path.rb
index c7d9196bf3fb09..7a482912cf3760 100644
--- a/spec/bundler/support/path.rb
+++ b/spec/bundler/support/path.rb
@@ -345,7 +345,7 @@ def git_ls_files(glob)
     end
 
     def tracked_files_glob
-      ruby_core? ? "libexec/bundle* lib/bundler lib/bundler.rb lib/rubygems/vendor/uri spec/bundler man/bundle*" : "exe/bundle exe/bundler lib/bundler lib/bundler.rb lib/rubygems/vendor/uri bundler.gemspec CHANGELOG-bundler.md LICENSE-bundler.md README-bundler.md"
+      ruby_core? ? "libexec/bundle* lib/bundler lib/bundler.rb lib/rubygems/vendor/uri lib/rubygems/vendor/securerandom spec/bundler man/bundle*" : "exe/bundle exe/bundler lib/bundler lib/bundler.rb lib/rubygems/vendor/uri lib/rubygems/vendor/securerandom bundler.gemspec CHANGELOG-bundler.md LICENSE-bundler.md README-bundler.md"
     end
 
     def lib_tracked_files_glob