Path Traversal in Grafana Loki
CVE-2026-21726
The CVE-2021-36156 fix validates the namespace parameter for path traversal sequences after a single URL decode, by double encoding, an attacker can read files at the Ruler API endpoint /loki/api/v1/rules/{namespace} Thanks to Prasanth Sundararajan for reporting this vulnerability.
Vulnerability class: Path Traversal (Directory Traversal)
EPSS: 0.004 (33.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
Affected products
- Grafana Loki — versions 2.3.0
Weakness classification (CWE)
References
- security@grafana.com (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-21726?
- CVE-2026-21726 is a medium-severity vulnerability in Grafana Loki, classified under Path Traversal. CVSS score: 5.3/10. Published 2026-04-15.
- How severe is CVE-2026-21726?
- Medium severity. CVSS v3 base score is 5.3 out of 10.