A vulnerability in Java Web Start may allow an untrusted application to elevate its privileges. For example an application may grant itself permissions to read and write local files that are accessible to the user running the Java Web Start application.

Sun acknowledges, with thanks, Peter Csepely, for bringing this issue to our attention.

This issue can occur in the following releases:

• Java Web Start in Java 2 Platform Standard Edition (J2SE) 5.0 Update 5 and earlier 5.0 releases for Windows, Solaris and Linux

Note: Java Web Start in SDK and JRE 1.4.x and earlier, and Java Web Start 1.0.1_02 and earlier are not affected by this issue.

To determine the version of Java on a system, the following command can be run:

    % java -fullversion
    java full version "1.5.0_02-b09"

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

To work around the described issue, disable Java Web Start applications from being launched from a web browser as follows:

For Internet Explorer:

1. Right click on the "Start" button and select "Explore"
2. In the "Start Menu" window, select "Tools" => "Folder Options"
3. From the "Folder Options" window, select the "File Types" tab
4. From the "Registered File Types" window, scroll down and locate the "JNLP - JNLP File"
5. Select the "JNLP - JNLP File" and click the "Delete" button

For Mozilla:

1. Select "Preferences" under the browser's "Edit" menu
2. In the "Preferences" window, select "Helper Applications" located under the "Navigator" category
3. Under "Files types", scroll down and locate "application/x-java-jnlp-file"
4. Select "application/x-java-jnlp-file" and click the "Remove" button

Notes:

1. On Microsoft Windows, applications may also be launched from the desktop icon or Start Menu if a shortcut was previously created for an application. Unknown applications should not be launched through the desktop icon or the Start Menu. Shortcuts can be removed by using the Java Web Start Application Manager through the "Application/Remove Shortcut" menu item. For more information, see:

• http://java.sun.com/j2se/1.5.0/docs/guide/javaws/developersguide/overview.html#jws

2. It is also possible to launch applications through the command line in Windows, Solaris, and Linux. Unknown applications should not be launched through the command line. Sites may consider renaming the Java Web Start launcher ("javaws.exe" for Windows and "javaws" for Solaris and Linux) to prevent Java Web Start from launching. The launcher can be found at:

Windows:

    C:\Program Files\java\j2re1.5.0\javaws\javaws.exe

Solaris (if installed using pkg):

    /usr/bin/javaws

Linux (if installed using rpm):

    /usr/java/jre1.5.0/bin/javaws

This issue is addressed in the following releases:

• Java Web Start in Java 2 Platform Standard Edition (J2SE) 5.0 Update 6 and later for Windows, Solaris, and Linux

J2SE 5.0 is available for download at the following links:

• http://java.sun.com/j2se/1.5.0/download.jsp
• http://java.com

Note: It is recommended that affected versions be removed from your system. For more information, please see the installation notes on the respective java.sun.com download pages.

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