CVE-2021-31909
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 · uneditedIn JetBrains TeamCity before 2020.2.3, argument injection leading to remote code execution was possible.
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 confidenceAn argument injection vulnerability in JetBrains TeamCity versions prior to 2020.2.3 allows remote attackers to inject malicious arguments into system commands, leading to arbitrary code execution on the affected server.
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< 2020.2.3CVSS 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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Locate TeamCity version numberAccess the TeamCity web interface and navigate to Administration > Server Administration > Server Information, or check the buildServer.properties file typically located in <TeamCity home>/conf/ directory for the version propertyAffected if The displayed version number is lower than 2020.2.3
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Identify TeamCity installation directoryLocate the TeamCity installation root directory, commonly found at /opt/teamcity, C:\TeamCity on Windows, or the directory where the TeamCity server process runsAffected if The version file or metadata within this directory shows a version prior to 2020.2.3
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Verify server accessibilityConfirm whether the TeamCity web interface is accessible from untrusted networks or the internet by reviewing firewall rules and network exposure settingsAffected if The server is network-accessible and the TeamCity version is below 2020.2.3 - an argument injection could be exploited remotely
The environment is affected if the installed TeamCity version is lower than 2020.2.3 and the server is network-accessible, as remote attackers could inject malicious arguments into system commands.
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 · scoped2020.2.3
Upgrade JetBrains TeamCity to version 2020.2.3 or later to remediate this vulnerability.
2020.2.3 or later
- 1. Back up the TeamCity data directory and database before upgrading
- 2. Download TeamCity 2020.2.3 or a later stable version from the official JetBrains website
- 3. Stop the TeamCity server service
- 4. Install the new TeamCity version following the standard upgrade procedure
- 5. Start the TeamCity server service
- 6. Verify the TeamCity web interface is accessible and all builds are functioning normally
- 7. Confirm the installed version by checking About > TeamCity version in the web UI
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-31909 — 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-2021-31909 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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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.
- 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