dbcve.org
Templating EngineApplication · Jenkins

CVE-2021-21646

HIGH · 8.8 CVSS v3.1 Published 2021-04-21
Fix available
A fix is available. Upgrade to after 2.1 or later.
See remediation →
94/100
Remediation priority · Urgent
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
Jenkins Templating Engine Plugin 2.1 and earlier does not protect its pipeline configurations using Script Security Plugin, allowing attackers with Job/Configure permission to execute arbitrary code in the context of the Jenkins controller JVM.

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 Jenkins Templating Engine Plugin versions 2.1 and earlier fails to protect its pipeline configurations using the Script Security Plugin sandbox. This allows any user with Job/Configure permission to inject and execute arbitrary Groovy code directly on the Jenkins controller JVM, bypassing all sandbox restrictions and gaining full controller-level access.

MitigationUpgrade the Jenkins Templating Engine Plugin to the latest version and verify that Script Security Plugin integration is properly enabled for all templating engine configurations.

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
Templating EngineApplication
Affected:<= 2.1

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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. Verify Jenkins Templating Engine Plugin is installed
    Navigate to Manage Jenkins > Manage Plugins > Installed and look for the Templating Engine plugin, or use the Jenkins CLI to list installed plugins
    Affected if The Templating Engine Plugin appears in the installed plugins list
  2. Determine the installed plugin version
    In the plugin manager, check the version column for the Templating Engine Plugin, or retrieve it via the Jenkins plugin API
    Affected if The version is 2.1 or earlier
  3. Identify pipelines using the Templating Engine
    Review existing Jenkins jobs and pipelines for configurations that utilize the Templating Engine (look for templates, pipeline configurations referencing template functionality)
    Affected if Any jobs or pipeline configurations are using the Templating Engine feature
  4. Check if sandbox protection is bypassed in pipeline configurations
    Examine the pipeline configurations that use Templating Engine for whether they allow Groovy code execution outside the Script Security sandbox (verify if sandbox restrictions are being circumvented in the job configuration)
    Affected if Pipeline configurations using Templating Engine permit arbitrary Groovy execution without sandbox enforcement

A user is affected if the Templating Engine Plugin version 2.1 or earlier is installed AND any jobs are configured to use the Templating Engine with sandbox protection bypassed

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 2.1
Interim mitigation

Upgrade the Jenkins Templating Engine Plugin to the latest version and verify that Script Security Plugin integration is properly enabled for all templating engine configurations.

Recommended fix Moderate confidence

Templating Engine Plugin version 2.2 or later (latest stable release)

  1. Navigate to Jenkins dashboard > Manage Jenkins > Manage Plugins
  2. Select the 'Available' tab and search for 'Templating Engine'
  3. If an update is available, select the plugin and click 'Download now and install after restart'
  4. Alternatively, download the newer .hpi file from the Jenkins plugin repository and upload it via 'Advanced' tab > 'Upload Plugin'
  5. Restart Jenkins to complete the installation
  6. Verify the new version is installed under Manage Plugins > Installed tab

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

Fix this in Templating Engine Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-21646 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2021-21646 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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