A flaw was discovered in the kvm (kernel virtual machine) subsystem's kvmapichasevents function. A unprivileged local user could exploit this flaw to cause a denial of service (system crash). (CVE-2015-4692) A flaw was discovered in how the Linux kernel handles invalid UDP checksums. A remote attacker could exploit this flaw to cause a denial of service using a flood of UDP packets with invalid checksums. (CVE-2015-5364) A flaw was discovered in how the Linux kernel handles invalid UDP checksums. A remote attacker can cause a denial of service against applications that use epoll by injecting a single packet with an invalid checksum. (CVE-2015-5366)

Karthikeyan Bhargavan discovered that NSS incorrectly handled state transitions for the TLS state machine. If a remote attacker were able to perform a machine-in-the-middle attack, this flaw could be exploited to skip the ServerKeyExchange message and remove the forward-secrecy property. (CVE-2015-2721) Watson Ladd discovered that NSS incorrectly handled Elliptical Curve Cryptography (ECC) multiplication. A remote attacker could possibly use this issue to spoof ECDSA signatures. (CVE-2015-2730) As a security improvement, this update modifies NSS behaviour to reject DH key sizes below 768 bits, preventing a possible downgrade attack. This update also refreshes the NSS package to version 3.19.2 which includes the latest CA certificate bundle.

Philip Pettersson discovered a privilege escalation when using overlayfs mounts inside of user namespaces. A local user could exploit this flaw to gain administrative privileges on the system.

Praveen Kariyanahalli, Ivan Fratric and Felix Groebert discovered that OpenSSL incorrectly handled memory when buffering DTLS data. A remote attacker could use this issue to cause OpenSSL to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2014-8176) Joseph Barr-Pixton discovered that OpenSSL incorrectly handled malformed ECParameters structures. A remote attacker could use this issue to cause OpenSSL to hang, resulting in a denial of service. (CVE-2015-1788) Robert Swiecki and Hanno Böck discovered that OpenSSL incorrectly handled certain ASN1TIME strings. A remote attacker could use this issue to cause OpenSSL to crash, resulting in a denial of service. (CVE-2015-1789) Michal Zalewski discovered that OpenSSL incorrectly handled missing content when parsing ASN.1-encoded PKCS#7 blobs. A remote attacker could use this issue to cause OpenSSL to crash, resulting in a denial of service. (CVE-2015-1790) Emilia Käsper discovered that OpenSSL incorrectly handled NewSessionTicket when being used by a multi-threaded client. A remote attacker could use this issue to cause OpenSSL to crash, resulting in a denial of service. (CVE-2015-1791) Johannes Bauer discovered that OpenSSL incorrectly handled verifying signedData messages using the CMS code. A remote attacker could use this issue to cause OpenSSL to hang, resulting in a denial of service. (CVE-2015-1792) As a security improvement, this update also modifies OpenSSL behaviour to reject DH key sizes below 768 bits, preventing a possible downgrade attack.

Xiong Zhou discovered a bug in the way the EXT4 filesystem handles fallocate zero range functionality when the page size is greater than the block size. A local attacker could exploit this flaw to cause a denial of service (system crash). (CVE-2015-0275) Wen Xu discovered a use-after-free flaw in the Linux kernel's ipv4 ping support. A local user could exploit this flaw to cause a denial of service (system crash) or gain administrative privileges on the system. (CVE-2015-3636)

As a security improvement, this update removes the export cipher suites from the default cipher list to prevent their use in possible downgrade attacks.

Alexandre Oliva reported a race condition flaw in the btrfs file system's handling of extended attributes (xattrs). A local attacker could exploit this flaw to bypass ACLs and potentially escalate privileges. (CVE-2014-9710) A memory corruption issue was discovered in AES decryption when using the Intel AES-NI accelerated code path. A remote attacker could exploit this flaw to cause a denial of service (system crash) or potentially escalate privileges on Intel base machines with AEC-GCM mode IPSec security association. (CVE-2015-3331) A flaw was discovered in the Linux kernel's IPv4 networking when using TCP fast open to initiate a connection. An unprivileged local user could exploit this flaw to cause a denial of service (system crash). (CVE-2015-3332)

A race condition between chown() and execve() was discovered in the Linux kernel. A local attacker could exploit this race by using chown on a setuid-user-binary to gain administrative privileges.

A flaw was discovered in the automatic loading of modules in the crypto subsystem of the Linux kernel. A local user could exploit this flaw to load installed kernel modules, increasing the attack surface and potentially using this to gain administrative privileges. (CVE-2013-7421) A flaw was discovered in the crypto subsystem when screening module names for automatic module loading if the name contained a valid crypto module name, eg. vfat(aes). A local user could exploit this flaw to load installed kernel modules, increasing the attack surface and potentially using this to gain administrative privileges. (CVE-2014-9644) Sun Baoliang discovered a use after free flaw in the Linux kernel's SCTP (Stream Control Transmission Protocol) subsystem during INIT collisions. A remote attacker could exploit this flaw to cause a denial of service (system crash) or potentially escalate their privileges on the system. (CVE-2015-1421) Marcelo Leitner discovered a flaw in the Linux kernel's routing of packets to too many different dsts/too fast. A remote attacker on the same subnet can exploit this flaw to cause a denial of service (system crash). (CVE-2015-1465)

Olivier Fourdan discovered that the X.Org X server incorrectly handled XkbSetGeometry requests resulting in an information leak. An attacker able to connect to an X server, either locally or remotely, could use this issue to possibly obtain sensitive information. (CVE-2015-0255) It was discovered that the X.Org X server incorrectly handled certain trapezoids. An attacker able to connect to an X server, either locally or remotely, could use this issue to possibly crash the server. This issue only affected Ubuntu 12.04 LTS. (CVE-2013-6424)