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CVE Record

CVE-2021-36157: An issue was discovered in Grafana Cortex through 1.9.0.

An issue was discovered in Grafana Cortex through 1.9.0. 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 Cortex will attempt to parse a rules file at that location and include some of the contents in the error message. (Other Cortex API requests can also be sent a malicious OrgID header, e.g., tricking the ingester into writing metrics to a different location, but the effect is nuisance rather than information disclosure.)

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-36157 affects Grafana Cortex through 1.9.0. A specially crafted tenant header could make Cortex read rule files from unintended filesystem paths and return some file content in an error message. The source bundle does not provide a CVSS score, confirmed fixed version, or evidence of active exploitation.

Executive priority

Prioritize confirming whether Cortex through 1.9.0 is deployed and exposed to untrusted tenants. The business concern is potential leakage of local file contents, but public severity and exploitation evidence are incomplete in the provided sources.

Technical view

Cortex uses X-Scope-OrgID to build paths for rules files. Directory traversal in that header can cause Cortex to attempt parsing a rules file outside the intended tenant path, leaking some contents through parser errors. Other APIs may misuse the header for nuisance effects, such as writing metrics elsewhere, but the cited description distinguishes that from information disclosure.

Likely exposure

Exposure is most likely in Cortex deployments through 1.9.0 where clients can supply X-Scope-OrgID to Cortex APIs. Risk depends on API reachability, tenant authentication, filesystem contents accessible to the Cortex process, and whether vendor guidance or PR #4375 has been applied.

Exploitation context

The CVE record describes a crafted header and directory traversal effect, but the bundle has no KEV listing and no cited evidence of exploitation in the wild. Treat exploitation status as unconfirmed unless additional current intelligence supports it.

Researcher notes

The core issue is path construction from X-Scope-OrgID without sufficient traversal protection. The public description names information disclosure through rule parsing errors and nuisance effects in other APIs. The bundle lacks CVSS, CWE mapping, exact fixed version, and exploit telemetry.

Mitigation direction

  • Identify Cortex deployments and confirm versions are not through 1.9.0.
  • Review Cortex project guidance and PR #4375 for the fixed release or patch.
  • Restrict Cortex API access to trusted, authenticated clients only.
  • Filter or reject suspicious X-Scope-OrgID values at trusted boundaries.
  • Reduce sensitive files readable by the Cortex runtime account.

Validation and detection

  • Inventory Cortex services and capture their running versions.
  • Review API gateway or proxy controls for X-Scope-OrgID handling.
  • Check whether fixes associated with Cortex PR #4375 are present.
  • Search logs for rejected or unusual X-Scope-OrgID values.
  • Confirm Cortex runtime filesystem permissions are least privilege.
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

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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-2021-36157 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

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