Withdrawn by the publisher.

On August 6, 2018, the Vulnerability Coordination team of the National Cyber Security Centre of Finland (NCSC-FI) and the CERT Coordination Center (CERT/CC) disclosed vulnerabilities in the TCP stacks that are used by the Linux and FreeBSD kernels. These vulnerabilities are publicly known as SegmentSmack. The vulnerabilities could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. An attack could be executed by using low transfer rates of TCP packets, unlike typical distributed denial of service (DDoS) attacks. The vulnerabilities are due to inefficient TCP reassembly algorithms in the TCP stacks that are used by the affected kernels. Linux Kernel Versions 4.9 and later and all supported versions of the FreeBSD kernel are known to be affected by these vulnerabilities. An attacker could exploit these vulnerabilities by sending a stream of packets that are designed to trigger the issue in an established TCP session with an affected device. A sustained DoS condition requires the attacker to maintain a continuous stream of malicious traffic. Due to the required use of an established session, an attack cannot be performed using spoofed IP addresses. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180824-linux-tcp ["https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180824-linux-tcp"]

Linux kernel versions 4.9+ can be forced to make very expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet which can lead to a denial of service.

Linux kernel versions 4.9+ can be forced to make very expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet which can lead to a denial of service.

Linux kernel versions 4.9+ can be forced to make very expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet which can lead to a denial of service. Linux kernel versions 4.9+ can be forced to make very expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet which can lead to a denial of service.

kernel: crypto: privilege escalation in skcipher_recvmsg function Kernel: hw: cpu: L1 terminal fault (L1TF) Kernel: hw: cpu: L1 terminal fault (L1TF) Kernel: speculative bounds check bypass store kernel: TCP segments with random offsets allow a remote denial of service (SegmentSmack) kernel: race condition in snd_seq_write() may lead to UAF or OOB-access kernel: mm: use-after-free in do_get_mempolicy function allows local DoS or other unspecified impact

kernel: Use-after-free in snd_pcm_info function in ALSA subsystem potentially leads to privilege escalation kernel: Use-after-free in snd_seq_ioctl_create_port() Kernel: hw: cpu: L1 terminal fault (L1TF) Kernel: hw: cpu: L1 terminal fault (L1TF) Kernel: speculative bounds check bypass store kernel: TCP segments with random offsets allow a remote denial of service (SegmentSmack) kernel: race condition in snd_seq_write() may lead to UAF or OOB-access kernel: kvm: vmx: host GDT limit corruption kernel: Race condition in sound system can lead to denial of service

Security update for the Linux Kernel

Affected: Ubuntu:14.04:LTS: linux, Ubuntu:14.04:LTS: linux-aws, Ubuntu:14.04:LTS: linux-lts-xenial, Ubuntu:16.04:LTS: linux, Ubuntu:16.04:LTS: linux-aws, Ubuntu:16.04:LTS: linux-azure, Ubuntu:16.04:LTS: linux-euclid, Ubuntu:16.04:LTS: linux-gcp, Ubuntu:16.04:LTS: linux-hwe, Ubuntu:16.04:LTS: linux-kvm and 9 more

Linux kernel versions 4.9+ can be forced to make very expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet which can lead to a denial of service.