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MinecraftApplication

CVE-2021-35054

HIGH · 7.5 CVSS v3.1 Published 2021-07-20
Fix available
A fix is available. Upgrade to 1.17.1 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
Minecraft before 1.17.1, when online-mode=false is configured, allows path traversal for deletion of arbitrary JSON files.

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

A path traversal vulnerability in Minecraft servers before version 1.17.1 allows remote attackers to delete arbitrary JSON files on the server filesystem when the online-mode=false configuration is set. The vulnerability exploits insufficient path validation in file deletion operations.

MitigationUpgrade Minecraft server to version 1.17.1 or later to patch the vulnerability. Alternatively, enable online-mode=true if compatible with server requirements, though upgrading is the recommended solution.

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
MinecraftApplication
Affected:< 1.17.1

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
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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. Identify the installed Minecraft server version
    Check the server console output on startup, the server.log file, or run the /version command in-game if you can connect. The version is typically displayed in the console when the server starts.
    Affected if The server version is any build earlier than 1.17.1 (e.g., 1.17.0, 1.16.5, 1.16.4, etc.)
  2. Locate the server.properties configuration file
    Find the server.properties file in the root directory of your Minecraft server installation. This file contains the runtime configuration settings.
    Affected if The server.properties file exists in the server directory.
  3. Verify the online-mode setting
    Open server.properties and locate the 'online-mode' configuration line. Check if it is set to 'online-mode=false'.
    Affected if The line 'online-mode=false' is present in server.properties, meaning the server is allowing offline authentication.

Your server is affected if it runs a version earlier than 1.17.1 AND has online-mode=false configured in server.properties.

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.

From vendor data
Upgrade available Upgrade to 1.17.1 or later
Fixed in 1.17.1
Interim mitigation

Upgrade Minecraft server to version 1.17.1 or later to patch the vulnerability. Alternatively, enable online-mode=true if compatible with server requirements, though upgrading is the recommended solution.

Fix this in Minecraft Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.

Scan for this in your stack

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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-2021-35054 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