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TeamcityApplication · Jetbrains

CVE-2023-34227

HIGH · 7.5 CVSS v3.1 Published 2023-05-31
Fix available
A fix is available. Upgrade to 2023.05 or later.
See remediation →
84/100
Remediation priority · High
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 2023.05 a specific endpoint was vulnerable to brute force attacks

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 confidence

JetBrains TeamCity before version 2023.05 contained a vulnerability where a specific authentication or login endpoint was susceptible to brute force attacks, allowing attackers to repeatedly guess credentials without adequate rate limiting or account lockout protections.

MitigationUpgrade TeamCity to version 2023.05 or later. If immediate upgrade is not possible, implement network-level rate limiting or IP blocking on the affected endpoint and enforce strong password policies.

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:< 2023.05

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
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 TeamCity installed version
    Access the TeamCity administration console, usually at /admin/admin.html?tab=version, or check the build server logs on startup which display the version number. Alternatively, check the TeamCity servers directory for version metadata.
    Affected if The installed version is any release before 2023.05 (e.g., 2023.04.x, 2022.x, older).
  2. Verify the authentication endpoints are network-accessible
    Identify if the TeamCity login pages (typically at /login.html or /user-login.html) are accessible from the network. Check reverse proxy or firewall rules to determine external or untrusted network exposure.
    Affected if The login endpoints are reachable from untrusted networks without additional authentication or VPN protection.
  3. Confirm rate limiting is not configured on authentication endpoints
    Review TeamCity configuration files (such as server.xml if using Tomcat) and any web server or proxy configuration (nginx, Apache, or cloud WAF) for rate limiting rules applied to the login paths. Look for settings like maxRequestsPerMinute or similar.
    Affected if No rate limiting rules are found for the TeamCity authentication endpoints.
  4. Check if account lockout policies are enabled
    Navigate to TeamCity administration under Administration > Authentication Settings or server configuration, and verify if there is a failed login attempt limit configured before accounts lock or delay is enforced.
    Affected if No account lockout or progressive delay after failed login attempts is configured in TeamCity.
  5. Review authentication logs for brute force patterns
    Examine TeamCity server logs (under /logs/teamcity-server.log or similar) for repeated failed login attempts from the same IP address or multiple usernames, which would indicate the vulnerability is being actively exploited.
    Affected if Logs show repeated failed login attempts without triggering lockout or significant delays.

You are affected if your TeamCity version is before 2023.05 AND the login endpoints are accessible without rate limiting or account lockout protections in place.

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 2023.05 or later
Fixed in 2023.05
Interim mitigation

Upgrade TeamCity to version 2023.05 or later. If immediate upgrade is not possible, implement network-level rate limiting or IP blocking on the affected endpoint and enforce strong password policies.

Recommended fix High confidence

TeamCity 2023.05 or later

  1. 1. Review the official JetBrains TeamCity upgrade documentation at https://www.jetbrains.com/help/teamcity/upgrade.html
  2. 2. Back up your TeamCity server data, including the <TeamCity home> directory and database
  3. 3. Download TeamCity 2023.05 or later from the official JetBrains website
  4. 4. Stop the TeamCity server
  5. 5. Run the TeamCity installer or extract the new version to your installation directory
  6. 6. Start the TeamCity server
  7. 7. Verify the upgrade was successful by logging into the web interface
  8. 8. Confirm the specific endpoint is no longer vulnerable to brute force attacks
Caveat Review JetBrains release notes for any configuration or feature changes between your current version and 2023.05

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

Fix this in Teamcity Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

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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-2023-34227 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