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DockerApplication

CVE-2016-6595

MEDIUM · 6.5 CVSS v3.0 Published 2017-01-04
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The SwarmKit toolkit 1.12.0 for Docker allows remote authenticated users to cause a denial of service (prevention of cluster joins) via a long sequence of join and quit actions. NOTE: the vendor disputes this issue, stating that this sequence is not "removing the state that is left by old nodes. At some point the manager obviously stops being able to accept new nodes, since it runs out of memory. Given that both for Docker swarm and for Docker Swarmkit nodes are *required* to provide a secret token (it's actually the only mode of operation), this means that no adversary can simply join nodes and exhaust manager resources. We can't do anything about a manager running out of memory and not being able to add new legitimate nodes to the system. This is merely a resource provisioning issue, and definitely not a CVE worthy vulnerability.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

SwarmKit 1.12.0 suffers from a memory exhaustion vulnerability where authenticated users can repeatedly join and quit nodes, causing the manager to consume excessive memory and preventing legitimate nodes from joining the cluster. The attack requires valid authentication credentials (secret tokens) to be exploited.

MitigationImplement rate limiting on join/quit operations and add resource constraints/quotas on the manager to prevent memory exhaustion from repeated node lifecycle events. Consider upgrading if a patched version exists.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
DockerApplication
Affected:= 1.12.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Docker version
    Run 'docker version' or 'docker --version' and look for the Server version. Confirm if it equals 1.12.0
    Affected if The installed Docker version is exactly 1.12.0
  2. Verify Swarm mode is enabled
    Run 'docker info' and look for Swarm: active. Also check 'docker node ls' to confirm manager is running
    Affected if Swarm mode is active and this node is a manager (or the manager being tested)
  3. Confirm secret token authentication is in use
    Check for configured secret tokens by reviewing swarm join tokens with 'docker swarm join-token -q worker' or 'docker swarm join-token -q manager'. Also check if '--secret' or '--external-ca' flags were used during swarm init
    Affected if Swarm join tokens exist and are accessible to potential attackers (even internally)
  4. Inspect manager memory usage
    Check memory consumption on the manager node using 'docker stats' or system tools like 'free -h', 'top', or 'ps aux | grep dockerd'
    Affected if Memory usage on the manager is abnormally high or continuously growing
  5. Check for node join/quit issues in logs
    Review Docker daemon logs (journalctl -u docker or /var/log/docker.log) for repeated node join and quit events, or failed legitimate node join attempts
    Affected if Logs show rapid node join/quit cycles or legitimate nodes failing to join due to resource exhaustion

You are affected if running Docker 1.12.0 with Swarm mode enabled and valid authentication tokens exist in an environment where untrusted users can trigger node join/quit operations repeatedly, resulting in elevated manager memory consumption.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement rate limiting on join/quit operations and add resource constraints/quotas on the manager to prevent memory exhaustion from repeated node lifecycle events. Consider upgrading if a patched version exists.

Fix this in Docker Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-6595 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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