DruidApplication · Apache
CVE-2021-26920
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 the Druid ingestion system, the InputSource is used for reading data from a certain data source. However, the HTTP InputSource allows authenticated users to read data from other sources than intended, such as the local file system, with the privileges of the Druid server process. This is not an elevation of privilege when users access Druid directly, since Druid also provides the Local InputSource, which allows the same level of access. But it is problematic when users interact with Druid indirectly through an application that allows users to specify the HTTP InputSource, but not the Local InputSource. In this case, users could bypass the application-level restriction by passing a file URL to the HTTP InputSource.
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 · high confidenceThe Druid HTTP InputSource improperly allows authenticated users to specify file:// URLs, enabling local file system access with Druid server process privileges. This bypasses application-level restrictions that only permit HTTP InputSource while blocking Local InputSource.
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
DruidApplication
< 0.22.0CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/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 checksWork through these to decide whether this CVE applies to you.
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Check installed Druid versionRun 'druid --version' or check the version file in the Druid installation directory, or query the Druid coordinator API endpoint /status/flagsAffected if Version is below 0.22.0
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Verify HTTP InputSource is accessible to authenticated usersReview Druid's input source configuration in the common.runtime.properties or druid.indexer.task.properties files, specifically looking for inputsource configurations that allow HTTP-based ingestionAffected if HTTP InputSource is enabled and accessible to authenticated users on a vulnerable version
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Check for file:// URL filtering in input validationReview the Druid configuration files for any input validation rules that restrict URL protocols, or examine if the HTTP InputSource accepts arbitrary URL protocols including file://Affected if No protocol filtering exists or file:// URLs are not explicitly blocked in HTTP InputSource configuration
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Review authentication and authorization settingsCheck the Druid authorizer configuration (typically in common.runtime.properties under druid.auth.authorizer) to determine if authenticated users have permissions that could enable arbitrary input source specificationAffected if Authenticated users have broad permissions that could allow them to specify input sources
A user is affected if running Apache Druid version below 0.22.0 with HTTP InputSource enabled and no explicit validation blocking file:// protocol URLs.
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 data0.22.0
Implement strict input validation to reject non-HTTP/HTTPS protocols in HTTP InputSource, and review authenticated user permissions to prevent local file access.
Fix this in Druid
Scoped from the published advisory
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-26920 — 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-2021-26920 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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- Version or environment caveats, and links to real fixes
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