CVE-2021-34086
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 Ultimaker S3 3D printer, Ultimaker S5 3D printer, Ultimaker 3 3D printer S-line through 6.3 and Ultimaker 3 through 5.2.16, the local webserver hosts APIs vulnerable to CSRF. They do not verify incoming requests.
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 confidenceThe local webserver on affected Ultimaker 3D printers (S3, S5, S-line through 6.3, and Ultimaker 3 through 5.2.16) hosts APIs vulnerable to Cross-Site Request Forgery (CSRF). These APIs do not verify the origin of incoming requests, allowing attackers to trick authenticated users into performing unintended actions via malicious web pages.
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<= 6.3<= 6.3<= 5.2.16CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 printer modelAccess the printer's web interface or check the physical label to confirm the model is Ultimaker S3, S5, or Ultimaker 3Affected if The model is not Ultimaker S3, S5, or Ultimaker 3 (other models are not affected by this CVE)
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Check the firmware versionLog into the printer's web interface and navigate to the settings or system information page, or check via the printer's touchscreen display under System > InformationAffected if Firmware version is 6.3 or lower for S3/S5, or 5.2.16 or lower for Ultimaker 3
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Verify the local webserver is accessibleAttempt to access the printer's web interface by entering the printer's IP address in a web browserAffected if The web interface is accessible and responds, meaning the CSRF-vulnerable APIs are exposed on the network
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Confirm CSRF protection is absent (optional manual verification)Submit a request to any API endpoint (such as /api/v1/print) from a different origin (e.g., via curl or a browser script) without including Origin or Referer headers and observe if the request is processed without rejectionAffected if The API accepts and processes requests without validating the Origin/Referer headers, indicating missing CSRF protection
The environment is affected if the device is an Ultimaker S3, S5, or Ultimaker 3 with firmware at or below 6.3 (S3/S5) or 5.2.16 (Ultimaker 3), and the local webserver is network-accessible.
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.
From vendor dataImplement CSRF protection mechanisms in the webserver APIs, such as anti-CSRF tokens, SameSite cookie attributes, and Origin/Referer header validation, requiring a firmware update from the vendor.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-34086 — 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-2021-34086 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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- 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
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