Netscape Portable Runtime 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 , and shared library linking. Network Security Services 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. These updated packages upgrade NSS from the previous version, 3.12.2, to a prerelease of version 3.12.4. The version of NSPR has also been upgraded from 4.7.3 to 4.7.4. Moxie Marlinspike reported a heap overflow flaw in a regular expression parser in the NSS library used by browsers such as Mozilla Firefox to match common names in certificates. A malicious website could present a carefully-crafted certificate in such a way as to trigger the heap overflow, leading to a crash or, possibly, arbitrary code execution with the permissions of the user running the browser. Note: in order to exploit this issue without further user interaction in Firefox, the carefully-crafted certificate would need to be signed by a Certificate Authority trusted by Firefox, otherwise Firefox presents the victim with a warning that the certificate is untrusted. Only if the user then accepts the certificate will the overflow take place. Dan Kaminsky discovered flaws in the way browsers such as Firefox handle NULL characters in a certificate. If an attacker is able to get a carefully-crafted certificate signed by a Certificate Authority trusted by Firefox, the attacker could use the certificate during a man-in-the-middle attack and potentially confuse Firefox into accepting it by mistake. Dan Kaminsky found that browsers still accept certificates with MD2 hash signatures, even though MD2 is no longer considered a cryptographically strong algorithm. This could make it easier for an attacker to create a malicious certificate that would be treated as trusted by a browser. NSS now disables the use of MD2 and MD4 algorithms inside signatures by default. These version upgrades also provide a fix for the following bug: * SSL client authentication failed against an Apache server when it was using the mod_nss module and configured for NSSOCSP. On the client side, the user agent received an error message that referenced "Error Code: - -12271" and stated that establishing an encrypted connection had failed because the certificate had been rejected by the host. On the server side, the nss_error_log under /var/log/httpd/ contained the following message: [error] Re-negotiation handshake failed: Not accepted by client!? Also, /var/log/httpd/error_log contained this error: SSL Library Error: -8071 The OCSP server experienced an internal error With these updated packages, the dependency problem which caused this failure has been resolved so that SSL client authentication with an Apache web server using mod_nss which is configured for NSSOCSP succeeds as expected. Note that if the presented client certificate is expired, then access is denied, the user agent is presented with an error message about the invalid certificate, and the OCSP queries are seen in the OCSP responder. Also, similar OCSP status verification happens for SSL server certificates used in Apache upon instance start or restart. All users of nspr and nss are advised to upgrade to these updated packages, which resolve these issues.