Container-Optimized OS: security advisories, deprecations and releases

Google's Linux operating system optimized for running containers on Compute Engine and Google Kubernetes Engine.

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HIGH NEW THIS WEEK Google Cloud Blog · 30 Oct 2026

GKE Private Service Connect API timeouts from three-layer networking bugs

GKE clusters using Private Service Connect in europe-west experienced intermittent API server timeouts caused by packet reordering, Envoy half-close behavior, and a Linux kernel TCP bug in FIN_WAIT_2 state handling.
HIGH ACT BY 23 OCT 2026 GKE security bulletins · 24 Oct 2026

GCP-2026-071: emSign CA compromise in GKE

Multiple emSign subordinate CA keys were stolen, exposing external TLS connections from GKE nodes and control plane to MitM. Internal cluster mTLS is safe. Patched GKE versions now distrust the bad CAs.

CVE-2026-111943
HIGH ACT BY 2 OCT 2026 GKE release notes · 3 Oct 2026

GKE 1.36.3+ FUSE CSI DaemonSet crash on older kernels

Control planes 1.36.3-gke.1244000 and later break the gcsfusecsi-node DaemonSet on Ubuntu and older COS node pools because /proc/sys/fs/fuse is absent.
HIGH Google Cloud release notes · 2 Oct 2026

Container Optimized OS multiple CVEs fixed

Fixed CVE-2026-0864, CVE-2026-56391, CVE-2026-90054 and 18 rsync CVEs across COS images.

CVE-2026-0864 CVE-2026-53784 CVE-2026-53786 CVE-2026-53789 CVE-2026-53791 CVE-2026-53795 CVE-2026-53797 CVE-2026-53798 CVE-2026-53799 CVE-2026-53800 CVE-2026-53801 CVE-2026-53802 CVE-2026-53803 CVE-2026-56391 CVE-2026-70455 CVE-2026-70457 CVE-2026-70459 CVE-2026-70461 CVE-2026-70463 CVE-2026-90054

LOW ACT BY 1 MAR 2027 endoflife.date · 2 Oct 2026

Container-Optimized OS cos-121 reaches end of life on 2027-03-01

Container-Optimized OS cos-121 reaches end of life on 2027-03-01, as listed by endoflife.date.

INFO endoflife.date · 4 Oct 2026

Container-Optimized OS cos-133 released

Container-Optimized OS cos-133 was released on 2026-09-28.

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