Release 6u17 is a new version that contains several bug and security fixes. The security related fixes include:

• A security repair to the Java Update mechanism on non-English versions, which was not updating the JRE when a new version was available.
• A security fix to a command execution vulnerability in the Java Runtime Environment Development Toolkit.
• A fix to a security vulnerability in the Java Web Start Installer.
• Corrections to multiple buffer and integer overflow defects in the Java Runtime Environment.
• A repair to a security vulnerability in the Java Runtime Environment with verifying HMAC  (Hash Message Authentication Code) digests.
• Patches to two security flaws in the Java Runtime Environment with decoding DER (Distinguished Encoding Rules) encoded data and parsing HTTP headers.

To see the entire list of fixed bugs and other changes, see the release notes.