CVE-2021-43202
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 2021.1.3, the X-Frame-Options header is missing in some cases.
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 confidenceIn JetBrains TeamCity before 2021.1.3, the X-Frame-Options HTTP security header is missing in certain responses. This header protects against clickjacking attacks by controlling whether the application can be embedded in iframes. Without it, attackers could embed the TeamCity interface in a malicious page and trick authenticated users into performing unintended actions.
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< 2021.1.3CVSS 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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Identify the installed TeamCity versionLog in to TeamCity as administrator and navigate to Administration > Server Configuration > Global Settings, or check the <TeamCity home>/buildserver.properties file for the version numberAffected if The installed version is lower than 2021.1.3 (e.g., 2021.1.2, 2021.1.1, 2021.1, etc.)
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Verify X-Frame-Options header presence in TeamCity web responsesUse a browser's developer tools (Network tab), curl, or a similar tool to send an HTTP request to your TeamCity server (e.g., GET /login.html) and inspect the response headers for X-Frame-OptionsAffected if The X-Frame-Options header is absent from the HTTP response headers, or is present only on some pages but missing on others
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Test iframe embedding capabilityCreate a simple HTML page with an iframe pointing to your TeamCity server URL (e.g., <iframe src="https://your-teamcity-server/login.html">) and attempt to load it in a browser, or inspect headers returned when requests include an X-Frame-Options checkAffected if The TeamCity pages can be rendered inside an iframe without being blocked, indicating the header is not set to DENY or SAMEORIGIN
You are affected if your TeamCity version is below 2021.1.3 AND the X-Frame-Options header is missing from HTTP responses, allowing your TeamCity interface to be embedded in iframes on external pages.
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 · scoped2021.1.3
Upgrade TeamCity to version 2021.1.3 or later. Alternatively, configure the web server or reverse proxy to add the X-Frame-Options: DENY (or SAMEORIGIN) header to all HTTP responses.
TeamCity 2021.1.3 or later
- Download TeamCity 2021.1.3 or later from the official JetBrains website
- Review the TeamCity upgrade documentation for your current version
- Backup your TeamCity data and configuration
- Stop the TeamCity server
- Install the new version following the upgrade guide
- Start the TeamCity server and verify the X-Frame-Options header is now present
- Verify all plugins and integrations work correctly after upgrade
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-43202 — 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-2021-43202 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