Multiple vulnerabilities were reported in the ASN.1 parsing code in OpenSSL. Attackers could exploit these issues to cause a denial of service or to execute arbitrary code.
Block external access at the network boundary, unless external parties require service.
If global access isn't needed, filter access to the affected computer at the network boundary. Restricting access to only trusted computers and networks might greatly reduce the likelihood of exploitation.
Implement multiple redundant layers of security.
Memory-protection schemes such as nonexecutable stack/heap configurations and randomly mapped memory segments may complicate exploitation of memory-corruption vulnerabilities.
Run all software as a nonprivileged user with minimal access rights.
Multiple applications may provide attack vectors for these issues. Always run software that does't explictly require elevated privileges as an unprivileged user with minimal access rights.
Please see the referenced advisories for more information.