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DruidApplication · Apache

CVE-2021-36749

MEDIUM · 6.5 CVSS v3.1 Published 2021-09-24
Fix available
A fix is available. Upgrade to 0.22.0 or later.
See remediation →
71/100
Remediation priority · Elevated
High EPSS Remotely reachable 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
In 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. This issue was previously mentioned as being fixed in 0.21.0 as per CVE-2021-26920 but was not fixed in 0.21.0 or 0.21.1.

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 confidence

The HTTP InputSource in Apache Druid allows authenticated users to read local filesystem files by supplying file:// URLs, bypassing application-level restrictions that only permit HTTP InputSource but not Local InputSource. This is a URL validation bypass where the HTTP InputSource fails to restrict access to only HTTP/HTTPS sources.

MitigationUpgrade to Druid 0.22.0 or later where this issue is properly fixed, or implement input validation to reject file:// URLs at the application layer.

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
Affected:< 0.22.0

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
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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Apache Druid installation and version
    Run 'druid -version' or check the package manager, or look for druid jars in the installation directory. Common paths: /opt/druid, /usr/local/druid, or check for 'druid-*' jars in the classpath.
    Affected if The installed version is any version of Apache Druid prior to 0.22.0
  2. Confirm HTTP InputSource functionality is accessible
    Check if the Druid ingestion API endpoint is exposed. Review Druid configuration files (commonly in conf/druid/_common or conf/runtime.properties) for enabled ingestion specs and look for inputSource configurations.
    Affected if HTTP InputSource is enabled and accessible to users through the ingestion or data source configuration API endpoints
  3. Verify authentication is configured for Druid
    Review Druid security configuration in conf/druid/_common/common.security.properties or check for authentication/authorization provider settings in the Druid console or config files.
    Affected if Authentication is enabled but allows untrusted users access to the ingestion API that processes inputSource specifications
  4. Check URL validation at the application layer
    Inspect any custom input validation filters or middleware that process inputSource URLs. Review application logs for any URL validation errors or lack thereof when non-HTTP URLs are submitted.
    Affected if The application layer lacks explicit validation to reject file:// URLs in HTTP InputSource requests
  5. Review network exposure of Druid APIs
    Check network listeners in Druid configuration (runtime.properties) to determine if the ingestion/coordinator APIs are exposed beyond trusted networks.
    Affected if The Druid API ports (typically 8081, 8082, 8083) are accessible from untrusted networks, allowing external authenticated users to submit malicious inputSource specifications

A user is affected if running Apache Druid version prior to 0.22.0 with HTTP InputSource enabled and accessible to authenticated users, where file:// URLs bypass URL validation.

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.

dbcve · scoped
Upgrade available Upgrade to 0.22.0 or later
Fixed in 0.22.0
Interim mitigation

Upgrade to Druid 0.22.0 or later where this issue is properly fixed, or implement input validation to reject file:// URLs at the application layer.

Recommended fix High confidence

Apache Druid 0.22.0 or later

  1. 1. Review current Druid deployment to confirm the version running (check druid jars, console, or configuration management)
  2. 2. Plan maintenance window for the upgrade, as this requires restarting Druid services
  3. 3. Download Apache Druid 0.22.0 or later from the official Apache Druid releases (downloads.apache.org)
  4. 4. Backup current Druid configuration files and any custom extensions
  5. 5. Stop all Druid services (coordinator, broker, historical, middleManager, overlord)
  6. 6. Replace Druid binaries with version 0.22.0+
  7. 7. Verify configuration compatibility (review release notes for any config changes)
  8. 8. Restart Druid services in the correct order (Zookeeper dependent services first, then others)
Caveat Review Druid 0.22.0 release notes for any breaking changes or migration requirements; some configuration parameters may have changed

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Druid Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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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-2021-36749 in production — separate from our analysis above.

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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