FULL PRODUCT VERSION :
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)

(Have also visually inspected corresponding file on 7u55 and 8u5)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]
(Don't believe to be OS specific)

A DESCRIPTION OF THE PROBLEM :
The message definition for InvalidCharRef in com/sun/org/apache/xerces/internal/impl/msg/XMLMessages.properties has been corrupted. In Java 7 and 8 it is defined as

InvalidCharRef = Character reference \"&#

while in Java 6 is was

InvalidCharRef=Character reference "&\#{0}" is an invalid XML character.

This makes the error less useful in Java 7 and 8.

REGRESSION. Last worked in version 6u45

ADDITIONAL REGRESSION INFORMATION:
java version "1.6.0_45"
Java(TM) SE Runtime Environment (build 1.6.0_45-b06)
Java HotSpot(TM) 64-Bit Server VM (build 20.45-b01, mixed mode)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
See executable test case.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
[Fatal Error] :1:12: Character reference "&#x1" is an invalid XML character.
Exception in thread "main" org.xml.sax.SAXParseException: Character reference "&#x1" is an invalid XML character.
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:246)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:284)
at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:124)
at XMLTest.main(XMLTest.java:10)


(witnessed in Java 6u45)
ACTUAL -
[Fatal Error] :1:12: Character reference "&#
Exception in thread "main" org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 12; Character reference "&#
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:257)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:347)
at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:121)
at XMLTest.main(XMLTest.java:10)


(witnessed in Java 7u51 and appears to be the case from inspecting the properties file in 7u55 and 8u5).

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.ByteArrayInputStream;
public class XMLTest {
    public static void main(String []args) throws Exception{
        DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new ByteArrayInputStream("<test>&#x1;</test>".getBytes()));
    }
}


---------- END SOURCE ----------