Several security issues were fixed in OpenSSL.
Guy Leaver discovered that OpenSSL incorrectly handled a ServerKeyExchange for an anonymous DH ciphersuite with the value of p set to 0. A remote attacker could possibly use this issue to cause OpenSSL to crash, resulting in a denial of service. This issue only applied to Ubuntu 15.10. (CVE-2015-1794)
7 December 2015
A security issue affects these releases of Ubuntu and its derivatives:
Several security issues were fixed in OpenSSL.
Guy Leaver discovered that OpenSSL incorrectly handled a ServerKeyExchange for an anonymous DH ciphersuite with the value of p set to 0. A remote attacker could possibly use this issue to cause OpenSSL to crash, resulting in a denial of service. This issue only applied to Ubuntu 15.10. (CVE-2015-1794)
Hanno Böck discovered that the OpenSSL Montgomery squaring procedure algorithm may produce incorrect results when being used on x86_64. A remote attacker could possibly use this issue to break encryption. This issue only applied to Ubuntu 15.10. (CVE-2015-3193)
Loïc Jonas Etienne discovered that OpenSSL incorrectly handled ASN.1 signatures with a missing PSS parameter. A remote attacker could possibly use this issue to cause OpenSSL to crash, resulting in a denial of service. (CVE-2015-3194)
Adam Langley discovered that OpenSSL incorrectly handled malformed X509_ATTRIBUTE structures. A remote attacker could possibly use this issue to cause OpenSSL to consume resources, resulting in a denial of service. (CVE-2015-3195)
It was discovered that OpenSSL incorrectly handled PSK identity hints. A remote attacker could possibly use this issue to cause OpenSSL to crash, resulting in a denial of service. This issue only applied to Ubuntu 12.04 LTS, Ubuntu 14.04 LTS and Ubuntu 15.04. (CVE-2015-3196)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to reboot your computer to make all the necessary changes.