リリース

日本語 準備中A large security maintenance release for the LTS channel: kernel jumps from 6.6.107 to 6.6.127 and closes hundreds of CVEs accumulated since the last LTS point release, plus a ca-certificates update and a local dev fix for arm64 Macs.

• securityApply the kernel update promptly — large CVE backlog closed

  This release rolls up roughly 20 kernel point releases (6.6.107 through 6.6.127), closing several hundred CVEs accumulated over that span. Treat this as a mandatory patch cycle rather than a routine bump — teams on 4081.3.6 or earlier have been running with months of unpatched kernel CVEs, some of which affect networking, filesystems, and memory management subsystems commonly hit in container workloads. Roll this out to fleets on the LTS channel as soon as your update ring allows.

• enhancementVerify TLS trust chains after ca-certificates 3.116→3.122 jump

  ca-certificates jumped from 3.116 to 3.122, spanning multiple NSS releases. If you pin or vendor CA bundles separately from the OS image, check for any removed or distrusted root certificates in that range that could break TLS validation for internal services or older endpoints.

• enhancementFaster local VM testing on Apple Silicon

  The QEMU launcher script now enables HVF acceleration on arm64 Macs (Flatcar#1901). If you develop or test Flatcar images locally on Apple Silicon, update your local scripts/tooling to pick this up — VM boot and test cycles should be noticeably faster.

日本語 準備中Flatcar stable-4593.2.0 is a large security + infrastructure release: 150+ kernel CVEs patched, openssh/openssl/curl/intel-microcode updated, and significant initrd/partition layout changes that need attention before upgrading.

• securityMass CVE remediation across kernel and userspace — update now

  Linux kernel patches cover 150+ CVEs, and userspace components (openssh 10.2_p1, openssl 3.5.4, curl 8.16.0, intel-microcode, gnupg, pam) each carry their own CVE fixes. This is a large security catch-up from Stable 4459.2.4. Any Flatcar node on stable should be updated promptly — the auto-update mechanism will handle it, but verify nodes are actually cycling through updates if you have update pauses configured.

• breakingsshd now uses OpenSSH upstream defaults including post-quantum key exchange

  sshd_config no longer hard-codes Ciphers, MACs, and KexAlgorithms; OpenSSH upstream defaults now apply, which includes post-quantum key exchange. If your environment requires specific legacy algorithms (e.g., for compliance tooling or older SSH clients), add drop-in config to /etc/ssh/sshd_config.d/ before upgrading. Test SSH connectivity after the update in a non-prod node first.

• breakingPartition layout changed; kernel module availability in first-stage initrd is reduced

  Partition sizes have grown: /boot to 1 GB, /usr to 2 GB, /oem to 1 GB. Existing nodes can still update, but new disk images will use the larger layout. If you have tight disk quotas, pre-provision or verify disk images have room. Also, the kernel+initrd on /boot is now half the size due to a two-stage initrd split — if any required drivers were only in the first-stage initrd, you may see boot issues. Report regressions to the Flatcar team immediately.