Updated nss and firefox packages fix security vulnerabilities

Mozilla developers and community members Jason Kratzer, Simon Giesecke, Philipp, and Christian Holler reported memory safety bugs present in Firefox ESR 78.3. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code (CVE-2020-15683). A use-after-free bug in the usersctp library was reported upstream. We assume this could have led to memory corruption and a potentially exploitable crash (CVE-2020-15969). A flaw was found in the way NSS handled CCS (ChangeCipherSpec) messages in TLS 1.3. This flaw allows a remote attacker to send multiple CCS messages, causing a denial of service for servers compiled with the NSS library. The highest threat from this vulnerability is to system availability. This flaw affects NSS versions before 3.58 (CVE-2020-25648).