dbcve.org
TeamcityApplication · Jetbrains

CVE-2021-37544

CRITICAL · 9.8 CVSS v3.1 Published 2021-08-06
Fix available
A fix is available. Upgrade to 2020.2.4 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
In JetBrains TeamCity before 2020.2.4, there was an insecure deserialization.

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

Insecure deserialization in JetBrains TeamCity before version 2020.2.4 allows remote attackers to execute arbitrary code via maliciously crafted serialized objects. The critical CVSS score indicates this vulnerability is easily exploitable and can lead to complete system compromise.

MitigationUpgrade TeamCity to version 2020.2.4 or later. If immediate patching is not feasible, enforce network segmentation to limit exposure and implement additional monitoring for suspicious activity patterns.

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
TeamcityApplication
Affected:< 2020.2.4

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
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 checks

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

  1. Identify installed TeamCity version
    Access the TeamCity web interface and navigate to the Administration > Server Administration page, or check the version displayed on the login page. Alternatively, inspect the TeamCity installation directory for a version file or check the server logs for startup version information.
    Affected if The installed version is any version prior to 2020.2.4 (e.g., 2020.2.3, 2020.1.x, 2019.x, etc.)
  2. Confirm TeamCity is network-accessible
    Verify that the TeamCity server is reachable over the network on its default port (typically 8111) or any configured HTTP/HTTPS port by attempting to access the web interface from another host or reviewing firewall rules and network exposure settings.
    Affected if The TeamCity web interface is accessible from untrusted networks, as this enables remote attackers to deliver maliciously crafted serialized objects.
  3. Check for deserialization endpoints
    Review TeamCity configuration files (such as server.xml or teamcity-startup.properties) for any exposed endpoints or services that handle Java serialized objects, or monitor network traffic for serialized object communications.
    Affected if Any TeamCity endpoint that accepts serialized Java objects is exposed, as this is the attack vector for this vulnerability.

You are affected if your TeamCity installation version is below 2020.2.4 and the server is network-accessible, allowing remote attackers to send maliciously crafted serialized objects to exploit the insecure deserialization flaw.

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 2020.2.4 or later
Fixed in 2020.2.4
Interim mitigation

Upgrade TeamCity to version 2020.2.4 or later. If immediate patching is not feasible, enforce network segmentation to limit exposure and implement additional monitoring for suspicious activity patterns.

Recommended fix High confidence

TeamCity 2020.2.4 or later

  1. 1. Back up the TeamCity server data directory and configuration files before proceeding
  2. 2. Stop the TeamCity server service
  3. 3. Download TeamCity 2020.2.4 or a later stable release from the official JetBrains website (www.jetbrains.com/teamcity/download)
  4. 4. Run the installer for the new version on the server
  5. 5. Follow the installation wizard to upgrade the existing TeamCity installation
  6. 6. Start the TeamCity server service after upgrade completes
  7. 7. Verify the TeamCity web interface is accessible and all projects are visible
  8. 8. Test critical build configurations to ensure normal operation
Caveat Review TeamCity release notes for any deprecated features or migration requirements between your current version and 2020.2.4

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

Fix this in Teamcity 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

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,080.

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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-2021-37544 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
  • 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