[java] Fix By.className()/By.id() misescaping non-ASCII leading digits

java/src/org/openqa/selenium/By.java

@@ -448,7 +448,11 @@ public final Parameters getRemoteParameters() {
 
     private String cssEscape(String using) {
       using = CSS_ESCAPE.matcher(using).replaceAll("\\\\$1");
-      if (!using.isEmpty() && Character.isDigit(using.charAt(0))) {
+      // CSS only requires the leading-digit escape for ASCII 0-9; non-ASCII Unicode digits
+      // (e.g. Arabic-Indic, fullwidth) are already valid identifier-start code points and must
+      // be left untouched, or they collide with the escape for a different ASCII digit.
+      char first = using.isEmpty() ? '\0' : using.charAt(0);
+      if (first >= '0' && first <= '9') {
         using = "\\" + (30 + Integer.parseInt(using.substring(0, 1))) + " " + using.substring(1);
       }
       return using;

java/src/org/openqa/selenium/remote/codec/w3c/W3CHttpCommandCodec.java

@@ -389,7 +389,11 @@ private Map<String, String> asElement(Object id) {
 
   private String cssEscape(String using) {
     using = CSS_ESCAPE.matcher(using).replaceAll("\\\\$1");
-    if (!using.isEmpty() && Character.isDigit(using.charAt(0))) {
+    // CSS only requires the leading-digit escape for ASCII 0-9; non-ASCII Unicode digits
+    // (e.g. Arabic-Indic, fullwidth) are already valid identifier-start code points and must
+    // be left untouched, or they collide with the escape for a different ASCII digit.
+    char first = using.isEmpty() ? '\0' : using.charAt(0);
+    if (first >= '0' && first <= '9') {
       using = "\\" + (30 + Integer.parseInt(using.substring(0, 1))) + " " + using.substring(1);
     }
     return using;

java/test/org/openqa/selenium/ByTest.java

@@ -122,4 +122,30 @@ void ensureIdIsSerializedProperly() {
         .containsEntry("using", "css selector")
         .containsEntry("value", "#one\\ two");
   }
+
+  @Test
+  void ensureLeadingAsciiDigitIsEscapedAsCodePoint() {
+    By by = By.className("5foo");
+
+    Json json = new Json();
+    Map<String, Object> blob = json.toType(json.toJson(by), MAP_TYPE);
+
+    assertThat(blob).containsEntry("using", "css selector").containsEntry("value", ".\\35 foo");
+  }
+
+  @Test
+  void ensureLeadingNonAsciiDigitIsNotMisescapedAsADifferentAsciiDigit() {
+    // U+0665 (Arabic-Indic digit five) has numeric value 5, but is not an ASCII digit.
+    // It is already a valid CSS identifier-start code point and must be passed through as-is,
+    // rather than being (mis)escaped to the same selector as an ASCII '5'.
+    By arabicIndicFive = By.className("٥foo");
+    By asciiFive = By.className("5foo");
+
+    Json json = new Json();
+    Map<String, Object> arabicBlob = json.toType(json.toJson(arabicIndicFive), MAP_TYPE);
+    Map<String, Object> asciiBlob = json.toType(json.toJson(asciiFive), MAP_TYPE);
+
+    assertThat(arabicBlob).containsEntry("using", "css selector").containsEntry("value", ".٥foo");
+    assertThat(arabicBlob.get("value")).isNotEqualTo(asciiBlob.get("value"));
+  }
 }

java/test/org/openqa/selenium/remote/codec/w3c/W3CHttpCommandCodecTest.java

@@ -0,0 +1,73 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.openqa.selenium.remote.codec.w3c;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.openqa.selenium.json.Json.MAP_TYPE;
+import static org.openqa.selenium.remote.http.Contents.string;
+
+import java.util.Map;
+import java.util.UUID;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+import org.openqa.selenium.json.Json;
+import org.openqa.selenium.remote.Command;
+import org.openqa.selenium.remote.DriverCommand;
+import org.openqa.selenium.remote.SessionId;
+import org.openqa.selenium.remote.http.HttpRequest;
+
+@Tag("UnitTests")
+class W3CHttpCommandCodecTest {
+
+  private final W3CHttpCommandCodec codec = new W3CHttpCommandCodec();
+  private final SessionId sessionId = new SessionId(UUID.randomUUID());
+  private final Json json = new Json();
+
+  @Test
+  void ensureLeadingAsciiDigitClassNameIsEscapedAsCodePoint() {
+    Map<String, Object> params = encodeFindElement("class name", "5foo");
+
+    assertThat(params).containsEntry("using", "css selector").containsEntry("value", ".\\35 foo");
+  }
+
+  @Test
+  void ensureLeadingAsciiDigitIdIsEscapedAsCodePoint() {
+    Map<String, Object> params = encodeFindElement("id", "5foo");
+
+    assertThat(params).containsEntry("using", "css selector").containsEntry("value", "#\\35 foo");
+  }
+
+  @Test
+  void ensureLeadingNonAsciiDigitClassNameIsNotMisescapedAsADifferentAsciiDigit() {
+    // U+0665 (Arabic-Indic digit five) has numeric value 5, but is not an ASCII digit.
+    // It must be passed through as-is, not (mis)escaped to the same selector as an ASCII '5'.
+    Map<String, Object> arabicIndicFive = encodeFindElement("class name", "٥foo");
+    Map<String, Object> asciiFive = encodeFindElement("class name", "5foo");
+
+    assertThat(arabicIndicFive)
+        .containsEntry("using", "css selector")
+        .containsEntry("value", ".٥foo");
+    assertThat(arabicIndicFive.get("value")).isNotEqualTo(asciiFive.get("value"));
+  }
+
+  private Map<String, Object> encodeFindElement(String strategy, Object value) {
+    HttpRequest request =
+        codec.encode(new Command(sessionId, DriverCommand.FIND_ELEMENT(strategy, value)));
+    return json.toType(string(request), MAP_TYPE);
+  }
+}