This patch release has several bug fixes, in particular the countermeasure for the recently disclosed timing-based attack on CBC mode TLS/SSL block cipher suites (http://www.mozilla.org/projects/security/pki/nss/news/vaudenay-cbc.html).
Please see the NSS 3.4.3 Release Notes (http://www.mozilla.org/projects/security/pki/nss/nss-3.4.3/nss-3.4.3-release-notes.html) for the bug that were fixed in NSS 3.4.3.
Wan-Teh Chang
