News · written 10 November 2026. A summary for readers, not technical advice — check the sources at the end for the details.

Docker Engine is what runs containers on a Linux server — the dockerd behind docker run. Docker released Docker Engine 29.9.3 on 3 November 2026. In Docker's words, it "includes fixes for multiple security vulnerabilities affecting Docker Engine and related components."

The security fixes

• CVE-2026-115538 — Swarm overlay networks could lose their encryption and spoofing protections after firewalld flushed Docker's iptables rules. GitHub rates it High. It matters if you run Swarm with encrypted overlay networks on a machine that uses firewalld.
• CVE-2026-115539 — in SwarmKit, a worker node's certificate could obtain a manager-node certificate shortly after a Swarm leader change.
• CVE-2026-116587 — excessive CPU use when parsing crafted RSA keys, in the go-jose library. GitHub rates it High.
• CVE-2026-116591 — a possible crash when decompressing zstd data, in the klauspost/compress library. GitHub rates it High.
• The update to BuildKit 0.34.2 fixes two more issues: a build that resolved the same Git source twice could crash the daemon, and a client with access to BuildKit's control API could set extended attributes outside BuildKit's own folder.

Other fixes

• The daemon no longer hangs on container, image and system requests under load.
• Literal << keys in YAML files are now written with quotes.

What it means for people who ship software

If you build or run your apps in Docker containers — on a home server or a small VPS — check which Docker Engine version you have. GitHub's advisory for the Swarm issue lists versions before 29.9.3 as affected and 29.9.3 as patched. Docker's release notes themselves give no upgrade advice and do not mention older release branches.

Sources

• Docker Docs — Docker Engine 29 release notes (29.9.3, 3 November 2026).
• moby on GitHub — Release docker-v29.9.3.
• GitHub — GHSA-6jhp-7446-hf7f (Swarm overlay networks and firewalld).

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