Red Hat: RHSA-2010:0165-01 Moderate: NSS TLS Session Handling Issue

Network Security Services (NSS) is a set of libraries designed to support the cross-platform development of security-enabled client and server applications. Applications built with NSS can support SSLv2, SSLv3, TLS, and other security standards.
Netscape Portable Runtime (NSPR) provides platform independence for non-GUI operating system facilities. These facilities include threads, thread synchronization, normal file and network I/O, interval timing, calendar time, basic memory management (malloc and free), and shared library linking.
A flaw was found in the way the TLS/SSL (Transport Layer Security/Secure Sockets Layer) protocols handled session renegotiation. A man-in-the-middle attacker could use this flaw to prefix arbitrary plain text to a client's session (for example, an HTTPS connection to a website). This could force the server to process an attacker's request as if authenticated using the victim's credentials. This update addresses this flaw by implementing the TLS Renegotiation Indication Extension, as defined in RFC 5746. (CVE-2009-3555)
Refer to the following Knowledgebase article for additional details about this flaw: Users of Red Hat Certificate System 7.3 and 8.0 should review the following Knowledgebase article before installing this update:
All users of NSS are advised to upgrade to these updated packages, which update NSS to version 3.12.6. This erratum also updates the NSPR packages to the version required by NSS 3.12.6. All running applications using the NSS library must be restarted for this update to take effect.