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CVE Record

CVE-2021-36156: An issue was discovered in Grafana Loki through 2.2.1.

An issue was discovered in Grafana Loki through 2.2.1. The header value X-Scope-OrgID is used to construct file paths for rules files, and if crafted to conduct directory traversal such as ae ../../sensitive/path/in/deployment pathname, then Loki will attempt to parse a rules file at that location and include some of the contents in the error message.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

Grafana Loki through 2.2.1 could treat a tenant header as part of a file path. A crafted value may cause Loki to read from an unintended location and expose some file contents in an error message. Business risk depends on whether vulnerable Loki services are reachable and what sensitive files exist nearby.

Executive priority

Prioritize this as a focused observability-platform remediation. It is not confirmed as actively exploited, but the potential impact is sensitive file disclosure from logging infrastructure, which often has broad operational visibility.

Technical view

The CVE describes directory traversal in Loki rules file path construction using X-Scope-OrgID. Loki may attempt to parse a rules file outside the intended directory and reflect some contents in the parsing error. The source bundle provides no CVSS, CWE, exploit maturity, or detailed configuration prerequisites.

Likely exposure

Exposure is most likely for organizations running Grafana Loki 2.2.1 or earlier. Risk is higher where Loki endpoints accepting tenant headers are reachable by untrusted users. The sources do not identify affected hosted services, operating systems, or specific deployment modes.

Exploitation context

The source bundle does not report active exploitation, and CISA KEV status is false. Public references describe the issue and a related Loki pull request and v2.3.0 release. Treat exploitability as plausible but not confirmed from these sources.

Researcher notes

Evidence is limited to the CVE description, a Grafana Loki PR reference, and the v2.3.0 release reference. The bundle does not include CVSS, patch diff details, affected configurations, or proof of exploitation. Avoid assuming broader Grafana product impact beyond Loki through 2.2.1.

Mitigation direction

  • Inventory Grafana Loki deployments and identify versions through 2.2.1.
  • Review Grafana Loki v2.3.0 release notes and PR 4020 for vendor fix context.
  • Move affected deployments to a vendor-supported fixed release after change testing.
  • Restrict access to Loki endpoints that accept tenant-scope headers.
  • Review vendor guidance before applying compensating controls.

Validation and detection

  • Confirm deployed Loki versions across production, staging, and observability clusters.
  • Check whether untrusted clients can reach Loki APIs using tenant headers.
  • Review logs for unusual tenant header values or rule parsing errors.
  • Verify upgraded systems no longer run Loki 2.2.1 or earlier.
  • Document any exposed instances and remediation status.
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

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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description · low confidence lookup

File access behavior lookup

The CVE wording references file access or upload behavior, so file telemetry and web shell 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 · low confidence lookup

CVE-2021-36156 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
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.