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NomadApplication · Hashicorp

CVE-2020-27195

CRITICAL · 9.1 CVSS v3.1 Published 2020-10-22
Fix available
A fix is available. Upgrade to after 0.12.5 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
HashiCorp Nomad and Nomad Enterprise version 0.9.0 up to 0.12.5 client file sandbox feature can be subverted using either the template or artifact stanzas. Fixed in 0.12.6, 0.11.5, and 0.10.6

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 · high confidence

The client file sandbox in HashiCorp Nomad, designed to restrict file access to a specific directory for jobs, can be subverted through the template or artifact stanzas. This allows path traversal or file inclusion attacks, enabling unauthorized read/write access to files outside the intended sandbox directory.

MitigationUpgrade Nomad to version 0.12.6, 0.11.5, or 0.10.6 or later to remediate the sandbox bypass vulnerability.

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
NomadApplication
Affected:>= 0.9.0, <= 0.10.5>= 0.11.0, <= 0.11.4>= 0.12.0, <= 0.12.5

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
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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. Determine Nomad server version
    Run `nomad version` on the Nomad server host to retrieve the installed version string.
    Affected if The displayed version falls within >= 0.9.0 to <= 0.10.5, >= 0.11.0 to <= 0.11.4, or >= 0.12.0 to <= 0.12.5.
  2. Identify jobs using template stanzas
    Run `nomad job status` to list all jobs, then for each job run `nomad job spec -job <job_name>` to inspect the job specification. Look for `template` blocks that fetch files from the client filesystem.
    Affected if Any registered job contains a `template` stanza with a `source`, `destination`, or `data` field that could reference paths outside the intended sandbox directory.
  3. Identify jobs using artifact stanzas
    Run `nomad job status` to list jobs, then inspect job specs as above. Look for `artifact` blocks that specify `source` paths pointing to local files.
    Affected if Any registered job contains an `artifact` stanza with a `source` field referencing local file paths that could escape the sandbox.
  4. Review sandbox configuration in job specifications
    Examine job spec files for `volume_mount` or `host_volume` stanzas that bind mount directories from the host into the task. These indicate the file sandbox is in use.
    Affected if Jobs are using host volume mounts or file-based template/artifact stanzas while running an affected Nomad version.

You are affected if your Nomad version is between 0.9.0-0.10.5, 0.11.0-0.11.4, or 0.12.0-0.12.5 AND you have jobs that use template or artifact stanzas with file paths.

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.

dbcve · scoped
Upgrade available Upgrade to a release after 0.12.5
Interim mitigation

Upgrade Nomad to version 0.12.6, 0.11.5, or 0.10.6 or later to remediate the sandbox bypass vulnerability.

Recommended fix High confidence

Nomad 0.12.6 (for 0.12.x), 0.11.5 (for 0.11.x), or 0.10.6 (for 0.10.x)

  1. 1. Identify your current Nomad version by running `nomad version`
  2. 2. Determine which version branch you are on (0.10.x, 0.11.x, or 0.12.x)
  3. 3. If on 0.10.x branch, upgrade to Nomad 0.10.6
  4. 4. If on 0.11.x branch, upgrade to Nomad 0.11.5
  5. 5. If on 0.12.x branch, upgrade to Nomad 0.12.6
  6. 6. Test the upgrade in a non-production environment first
  7. 7. Apply the upgrade to production nodes, following standard Nomad upgrade procedures

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nomad Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,800
Get the upgrade done

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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-2020-27195 in production — separate from our analysis above.

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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
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data