Path traversal in Grafana Loki

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2021-36156: 1.48% estimated exploitation activity in the next 30 days; percentile 73.90 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

2 Sep 2021, 22:00 UTC

Last modified by the source

1 Feb 2023, 05:06 UTC

Source last checked

26 Oct 2026, 14:54 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-grj5-8x6q-hc9q

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# Patch Next advisory brief: CVE-2021-36156

Advisory: Path traversal in Grafana Loki
IDs: CVE-2021-36156, GHSA-grj5-8x6q-hc9q
Record: https://patchnext.com/advisories/cve-2021-36156 (revision 1, source checked 26 Oct 2026, 14:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/grafana/loki 2.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/grafana/loki: affected < 2.3.0; fixed in 2.3.0

## Suggested inspection (read-only)
- Go github.com/grafana/loki: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/grafana/loki.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-grj5-8x6q-hc9q (GitHub-reviewed advisory GHSA-grj5-8x6q-hc9q lists affected ranges: Go github.com/grafana/loki >=0 <2.3.0)

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