What’s Vulnerable › Vulnerabilities
CVE-2026-21726: Loki Path Traversal - CVE-2021-36156 Bypass
- Severity: medium (CVSS 5.3 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.4% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-04-15 · updated 2026-10-26
- Weakness: CWE-22
Description
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.
Affected products
- Grafana Loki: before 3.6.4 — fixed in 3.6.4
How to fix
Upgrade to a fixed version: Grafana Loki 3.6.4. Check the vendor advisory for mitigations.
References
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