The Java Runtime Environment UTF-8 Decoder May Allow Multiple Representations of UTF-8 Input

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The Java Runtime Environment UTF-8 decoder may allow multiple representations of UTF-8 input:

1. Impact

The UTF-8 (Unicode Transformation Format-8) decoder in the Java Runtime Environment (JRE) accepts encodings that are longer than the "shortest" form. This behavior is not a vulnerability in Java SE. However, it may be leveraged to exploit systems running software that relies on the JRE UTF-8 decoder to reject non-shortest form sequences. For example, non-shortest form sequences may be decoded into illegal URIs, which may then allow files that are not otherwise accessible to be read, if the URIs are not checked following UTF-8 decoding.

2. Contributing Factors

This issue can occur in the following Java SE and Java SE for Business releases for Solaris, Windows and Linux:

• JDK and JRE 6 Update 10 or earlier
• JDK and JRE 5.0 Update 16 or earlier
  
• SDK and JRE 1.4.2_18 or earlier

and the following Java SE releases for Solaris, Windows and Linux:

• SDK and JRE 1.3.1_23 or earlier
  

To determine the default version of the JRE that Internet Explorer uses:

1. Click "Tools" in the Menu Bar at the top of the browser
2. Select "Sun Java Console"

The first two lines in the console display the version of Java Plug-in and JRE that Internet Explorer uses.

To determine the default version of the JRE that Mozilla or Firefox browsers use, visit the URL "about:plugins".

The browser will display a page called "Installed plug-ins" which lists the version of the Java Plug-in, as shown in the following example:

    Java(TM) Plug-in 1.5.0_11-b03

(Indicating that the JRE version the browser uses is 1.5.0_11)

3. Symptoms

There are no reliable symptoms that would indicate the described issue has been exploited.

4. Workaround

There is no workaround for this issue. Please see the Resolution section below.

5. Resolution

This issue is addressed in the following Java SE and Java SE for Business releases for Solaris, Windows and Linux:

• JDK and JRE 6 Update 11 or later
• JDK and JRE 5.0 Update 17 or later
  
• SDK and JRE 1.4.2_19 or later

and the following Java SE releases for Solaris, Windows and Linux:

• SDK and JRE 1.3.1_24 or later
  

Java SE releases are available at:

JDK 6 Update 11: 

• http://java.sun.com/javase/downloads/index.jsp

JRE 6 Update 11:

• http://java.sun.com/javase/downloads/index.jsp
• http://java.com/

and through the Java Update tool for Microsoft Windows users.

JDK 6 Update 11 is also available for Solaris in the following patches:

• Java SE 6: update 11 (as delivered in patch 125136-12)
  
• Java SE 6: update 11 (as delivered in patch 125137-12 (64bit))
• Java SE 6_x86: update 11 (as delivered in patch 125138-12)
• Java SE 6_x86: update 11 (as delivered in patch 125139-12 (64bit))

JDK and JRE 5.0 Update 17:

• http://java.sun.com/javase/downloads/index_jdk5.jsp

JDK 5.0 Update 17 is also available for Solaris in the following patches:

• J2SE 5.0: update 17 (as delivered in patch 118666-18)
  
• J2SE 5.0: update 17 (as delivered in patch 118667-18 (64bit))
  
• J2SE 5.0_x86: update 17 (as delivered in patch 118668-18)
  
• J2SE 5.0_x86: update 17 (as delivered in patch 118669-18 (64bit))
  

SDK and JRE 1.4.2:

• http://java.sun.com/j2se/1.4.2/download.html
  

Java SE for Business Releases:

• http://www.sun.com/software/javaseforbusiness/getit_download.jsp

Note 1: Java SE releases SDK and JRE 1.4.2 have completed the Sun End of Service Life (EOSL) process. Sun recommends that users upgrade to the latest Java SE release. Customers interested in continuing to receive critical fixes on SDK and JRE 1.4.2 are encouraged to migrate to Java SE for Business.

Note 2: SDK and JRE 1.3.1 have completed the Sun End of Service Life (EOSL) process and is only supported for customers with Solaris 8 and Vintage Support Offering support contracts (see: http://java.sun.com/j2se/1.3/download.html). Sun strongly recommends that users upgrade to the latest Java SE release.

Note 3: When installing a new version of the product from a source other than a Solaris patch, it is recommended that the old affected versions be removed from your system. To remove old affected versions on the Windows platform, please see:

• http://java.com/en/download/help/uninstall_java.xml
  

For more information on Security Sun Alerts, see Technical Instruction ID 213557.

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