Grafana Loki Path Traversal - CVE-2021-36156 Bypass

Medium
Advisory ID:CVE-2026-21726
Published:2026-01-26
Product:Loki
CVSS Score:5.3
CVSS Vector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Fixed Versions:
>=v3.6.4

Summary

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.