From 3b5163a890798c135442466fc35fd803e7232471 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Mon, 12 Oct 2026 16:37:32 +0200
Subject: [PATCH] Handle invalid encoding in JSON path keys

---
 lib/json/common.rb            | 5 ++++-
 test/json/json_parser_test.rb | 4 ++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/json/common.rb b/lib/json/common.rb
index 01a4be18c..4b2d6d87f 100644
--- a/lib/json/common.rb
+++ b/lib/json/common.rb
@@ -171,7 +171,10 @@ def build_json_path(segments)
         when Integer
           "[#{segment}]"
         when String, Symbol
-          if segment.match?(/\A[a-zA-Z\$\_][a-zA-Z\$\_0-9]*\z/)
+          if !segment.valid_encoding?
+            segment = segment.b.gsub(/["\\]/n, { '"' => '\\"', '\\' => '\\\\' }).force_encoding(Encoding::UTF_8)
+            %{["#{segment}"]}
+          elsif segment.match?(/\A[a-zA-Z\$\_][a-zA-Z\$\_0-9]*\z/)
             ".#{segment}"
           else
             segment = segment.to_s.gsub(/["\\]/, { '"' => '\\"', '\\' => '\\\\' })
diff --git a/test/json/json_parser_test.rb b/test/json/json_parser_test.rb
index 47d84b398..3607be33a 100644
--- a/test/json/json_parser_test.rb
+++ b/test/json/json_parser_test.rb
@@ -931,6 +931,10 @@ def test_parse_error_json_path
     assert_parse_error_at "$[4]", '[1,2,3,4,5'
     assert_parse_error_at "$[5]", '[1,2,3,4,5,'
     assert_parse_error_at "$[5]", '[1,2,3,4,5,]'
+
+    if RUBY_ENGINE != "jruby"
+      assert_parse_error_at %($["\xff"][1]), %({"\xff":[1,x]})
+    end
   end
 
   def test_parse_error_position