JenkinsApplication
CVE-2021-21693
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 · uneditedWhen creating temporary files, agent-to-controller access to create those files is only checked after they've been created in Jenkins 2.318 and earlier, LTS 2.303.2 and earlier.
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 confidenceThis is a Time-of-Check to Time-of-Use (TOCTOU) race condition vulnerability in Jenkins. When agents request temporary file creation on the controller, the access control check happens AFTER the file is created rather than before, allowing agents to potentially create files in locations they shouldn't have access to. This window between file creation and permission verification enables unauthorized file system access.
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
JenkinsApplication
< 2.303.3< 2.319CVSS 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
- High
CVSS:3.1/AV:N/AC:L/PR:N/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 checksWork through these to decide whether this CVE applies to you.
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Check the installed Jenkins versionNavigate to Manage Jenkins > About Jenkins or execute: java -jar jenkins.war --version (or check the version file in the Jenkins installation directory)Affected if The version is below 2.303.3 (LTS) or below 2.319 (weekly)
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Verify if Jenkins agents are configuredNavigate to Manage Jenkins > Manage Nodes. Check if any agents (nodes) are defined and connected.Affected if Any agents are configured and connected to the controller
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Confirm if the Jenkins remoting subsystem is activeCheck Manage Jenkins > System Information for 'jenkins.agent.connected' or look for active remoting connections in the logsAffected if Remoting connections are active between agents and the controller
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Inspect temporary file creation permissionsReview Jenkins logs (var/log/jenkins/jenkins.log) for any file creation operations involving agent-requested temporary files, particularly in system diagnostics or support bundlesAffected if Temporary file creation by agents is logged without prior permission validation
You are affected if your Jenkins version is below 2.303.3 (LTS) or below 2.319 and you have agents configured that communicate with the controller via remoting.
Generated from the published advisory. Verify against your own configuration.
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 · scoped2.303.32.319
Upgrade Jenkins to version 2.319 or later (LTS 2.303.3 or later) which implements proper permission checks before temporary file creation.
Jenkins 2.319 (weekly) or Jenkins LTS 2.303.3
- Upgrade Jenkins to version 2.319 or later, or to Jenkins LTS version 2.303.3 or later
- If using a package manager (apt, yum, brew), run the appropriate update command for your system
- Alternatively, download the WAR file from https://www.jenkins.io/download/ and deploy it to your Jenkins installation
- Restart Jenkins after the upgrade to apply the changes
- Verify the upgrade was successful by checking the Jenkins version in the web UI (Manage Jenkins > About Jenkins)
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Jenkins
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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 locallyCheck whether your project pulls in CVE-2021-21693 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-21693 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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