CVE-2021-43185
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 · uneditedJetBrains YouTrack before 2021.3.23639 is vulnerable to Host header injection.
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 confidenceHost header injection vulnerability in JetBrains YouTrack versions prior to 2021.3.23639 allows attackers to manipulate the Host header to inject malicious values, potentially leading to web cache poisoning, password reset link manipulation, or other attacks relying on the server trusting the Host header.
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< 2021.3.23639CVSS 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 if YouTrack is runningCheck running processes or services for 'youtrack' or look for YouTrack web service listening on common ports (typically 8080, 8443, or 80/443) using commands like 'netstat -ano | grep -E "8080|8443"' or 'tasklist' on WindowsAffected if YouTrack service is found running on the system
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Locate YouTrack installation directoryCommon locations include /opt/youtrack, /home/*/youtrack, or C:\Program Files\JetBrains\YouTrack. Check the service configuration or process properties for the actual installation pathAffected if YouTrack installation directory exists on the system
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Determine installed YouTrack versionIn the YouTrack installation directory, check for a version file such as 'product-info.json', 'version.txt', or the 'youtrack.jar' manifest. Alternatively, access the YouTrack web interface and look at the version displayed in the page footer or query the /api/version endpoint if availableAffected if A version number is found and is less than 2021.3.23639
If YouTrack is running and the installed version is below 2021.3.23639, the system is vulnerable to Host header injection attacks.
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 · scoped2021.3.23639
Upgrade YouTrack to version 2021.3.23639 or later; additionally, configure the server to validate and whitelist expected Host values to prevent injection attacks.
2021.3.23639 or later
- Check current YouTrack version in Administration > Application section
- Back up YouTrack database and configuration files before upgrading
- Download YouTrack version 2021.3.23639 or later from jetbrains.com
- Run the YouTrack installer/upgrader to apply the update
- Restart YouTrack service after upgrade completes
- Verify the application is running and accessible
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 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 $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-43185 — 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-2021-43185 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