RHSA-2009:1207: Critical: nspr and nss security update

Netscape Portable Runtime (NSPR) provides platform independence for non-GUIoperating system facilities. These facilities include threads, threadsynchronization, normal file and network I/O, interval timing, calendartime, basic memory management (malloc and free), and shared library linking.Network Security Services (NSS) is a set of libraries designed to supportthe cross-platform development of security-enabled client and serverapplications. 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 aprerelease of version 3.12.4. The version of NSPR has also been upgradedfrom 4.7.3 to 4.7.4.Moxie Marlinspike reported a heap overflow flaw in a regular expressionparser in the NSS library used by browsers such as Mozilla Firefox to matchcommon names in certificates. A malicious website could present acarefully-crafted certificate in such a way as to trigger the heapoverflow, leading to a crash or, possibly, arbitrary code execution withthe permissions of the user running the browser. (CVE-2009-2404)Note: in order to exploit this issue without further user interaction inFirefox, the carefully-crafted certificate would need to be signed by aCertificate Authority trusted by Firefox, otherwise Firefox presents thevictim with a warning that the certificate is untrusted. Only if the userthen accepts the certificate will the overflow take place.Dan Kaminsky discovered flaws in the way browsers such as Firefox handleNULL characters in a certificate. If an attacker is able to get acarefully-crafted certificate signed by a Certificate Authority trusted byFirefox, the attacker could use the certificate during a man-in-the-middleattack and potentially confuse Firefox into accepting it by mistake.(CVE-2009-2408)Dan Kaminsky found that browsers still accept certificates with MD2 hashsignatures, even though MD2 is no longer considered a cryptographicallystrong algorithm. This could make it easier for an attacker to create amalicious certificate that would be treated as trusted by a browser. NSSnow disables the use of MD2 and MD4 algorithms inside signatures bydefault. (CVE-2009-2409)All users of nspr and nss are advised to upgrade to these updated packages,which resolve these issues.