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CVE Record

CVE-2021-36749: Apache Druid: The HTTP inputSource allows authenticated users to read data from other sources than intended (incomplete fix of CVE-2021-26920)

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

Apache Druid 0.21.1 and earlier can let authenticated users read data sources an application intended to block, including local files readable by the Druid server process. The risk is highest where another application exposes Druid ingestion and allows HTTP input sources while trying to forbid local-file input.

Executive priority

Prioritize remediation where Druid ingestion is delegated to customers, analysts, or internal users through another application. Direct-admin-only deployments are lower urgency, but still need version review because sources confirm the prior fix was incomplete.

Technical view

The Druid ingestion HTTP InputSource could read unintended sources because the earlier CVE-2021-26920 fix was incomplete. Authenticated users may bypass application-level restrictions by supplying non-HTTP source locations to the HTTP InputSource, causing reads with Druid server privileges. Sources do not provide CVSS, CWE, or confirmed fixed-version details.

Likely exposure

Deployments using Apache Druid 0.21.1 or earlier are in scope, especially multi-user or application-mediated ingestion workflows where users can influence HTTP InputSource configuration.

Exploitation context

The bundle reports an authenticated misuse path but does not cite active exploitation, public weaponization, or KEV listing. Treat this as access-control bypass and unintended file/data exposure risk, not confirmed internet-scale exploitation.

Researcher notes

This is an authenticated access-control boundary issue around ingestion source handling. The important research question is whether application-level restrictions assume HTTP InputSource cannot reach local or unintended sources. Evidence does not include exploit prevalence, CVSS, or a named fixed version.

Mitigation direction

  • Inventory Apache Druid versions and flag 0.21.1 or earlier.
  • Review Apache advisory guidance before choosing an upgrade or workaround.
  • Restrict who can submit ingestion specs or inputSource settings.
  • Block untrusted applications from passing arbitrary HTTP InputSource values.
  • Review Druid server file permissions and reduce readable sensitive files.

Validation and detection

  • Confirm whether users can influence Druid ingestion inputSource configuration.
  • Identify application layers that allow HTTP InputSource but block Local InputSource.
  • Review Druid audit logs for unusual ingestion source locations.
  • Check Druid process permissions against sensitive local paths.
  • Verify remediation against Apache's official advisory or release guidance.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Privilege behavior lookup

The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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CVE-2021-36749 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Apache Software FoundationApache Druid0.21.1 and earlierListed
Weakness

CWE details

No CWE listed

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