Container-Optimized OS Release Notes: Milestone 77

Current Status

Image Family cos-77-lts
Deprecated After Jan 11, 2021
Kernel 4.19.112
Kubernetes v1.15.3
Docker v19.03.1



Date: Jan 11, 2021
  • Fixed CVE-2020-29660 in the Linux kernel.
  • Fixed CVE-2020-29661 in the Linux kernel.


Date: Dec 02, 2020
  • Fixed CVE-2020-15257 in containerd.


Date: Oct 26, 2020
  • Fixed CVE-2020-14356.


Date: Oct 12, 2020
  • Added PPP loadable modules back, which were removed in cos-77-12371-1072-0.
  • Moved Docker's "registry-mirrors" configuration to the dockerd command line to address Kubernetes cluster provisioning errors.


Date: Oct 08, 2020
  • Moved the configuration of Docker's "registry-mirrors" option from the dockerd command line to /etc/docker/daemon.json. This should allow users to configure a custom registry mirror, which can be useful when responding to recent Docker Hub free tier changes.
  • Fixed CVE-2020-15157 in containerd.


Date: Sep 05, 2020
  • Fixed Linux kernel vulnerability CVE-2020-14386 by fixing an integer overflow issue in tpacket_rcv.


Date: Aug 21, 2020
  • Enabled utmp in systemd to allow creation of utmp files.


Date: Aug 10, 2020
  • Disabled CONFIG_PPP to mitigate Linux Kernel CVE-2020-14416.
  • Fixed CVE-2020-15705 in grub.


Date: July 30, 2020
  • Removed the metrics daemon to address an issue where it would periodically cause CPU usage spikes in some cases.


Date: July 13, 2020
  • Added rsync back into the image, which was removed in cos-dev-77-12293-0-0.
  • Mount /var/lib/containerd with exec option.
  • Moved Kernel source to
  • Fixed CVE-2019-9169.


Date: June 16, 2020
  • Updated toolbox base container image to include security patches.


Date: May 26, 2020
  • Fixed a few OS Login CVEs: CVE-2020-8903, CVE-2020-8907, CVE-2020-8933.


Date: May 21, 2020
  • Fixed a Stackdriver Monitoring agent bug where not all mounted disk partitions has their usage reported.


Date: Apr 29, 2020
  • Fixed a kernel bug where eBPF programs can cause softlockups.


Date: Apr 29, 2020
  • Disabled `accept_ra` on all interfaces by default.


Date: Apr 05, 2020
  • Upgraded the Linux kernel to v4.19.112.
  • Backported systemd patch ba0d56f55 to address an issue that resulted in leaked mount units.


Date: Mar 17, 2020
  • Fixed a bug where DHCP is not started after link flaps.
  • Removed size limit on /etc/ to fix cluster creation failure because of large number of addons.
  • Upgraded the Linux kernel to v4.19.109.


Date: Feb 21, 2020
  • Upgraded the Linux kernel to v4.19.104.
  • Fixed TCP empty skb at the tail of the write queue bug in kernel.


Date: Feb 12, 2020
  • Enabled some QoS and Fair Queuing options in the Linux kernel.
  • Upgraded the Linux kernel to v4.19.102.
  • Upgraded runc to 1.0.0-rc10. This resolves CVE-2019-19921.


Date: Jan 07, 2020
  • Backported fix for Linux kernel CVE-2019-19072.
  • Fixed CFS quota throttling issue.
  • Upgraded the Linux kernel to v4.19.91.


Date: Oct 31, 2019
  • Increased sysctl net.ipv4.tcp_limit_output_bytes to 1048576.
  • Fixed the problem of spawning 8 runc state process for every exec on containerd. This was leading to high cpu utilization.
  • Fixed the unnecessary creation of two separate test slices (resulting in 4 systemd log messages total + runtime overhead) for every runc execution.
  • Fixed an issue in runc that resulted in unnecessary CPU consumption. Upgraded the Linux kernel to v4.19.80.
  • Fixed a performance regression in completely fair scheduler (CFS).


Date: Oct 9, 2019
  • Upgraded the Linux kernel to 4.19.76.
  • Backported a kernel patch to ensure the cfs cgroup quota/period ratio always stays the same. This addresses a Kubernetes issue where the pod cgroup could be changed into an inconsistent state.
  • Backported a kernel patch to fix performance regression in wbt scale_up/scale_down.

cos-77-12371-76-0 (vs Milestone 73)

Date: Sep 27, 2019

New features

  • Enabled Shielded VM by default. Secure boot is not enabled by default.
  • Enabled cgroup v2 hybrid mode in systemd.
  • Added support for the virtio balloon driver.
  • Added the node-problem-detector package.
  • Added the conntrack-tools package.
  • Added the xfsprogs package.

Package updates

  • Upgraded systemd to version 239.
  • Upgraded the Linux kernel to version 4.19.
  • Upgraded Docker to version 19.03.
  • Upgraded Kubelet to version 1.15.
  • Upgraded the compute-image-packages to version 20190304.
  • Upgraded openssl to version 1.0.2r.
  • Upgraded openssh to version 7.9p1.
  • Changed kernel compiler from gcc to clang.