Vulnerability · Published Apr 15, 2026 · Assigned by GRAFANA
CVE-2026-21726Loki Path Traversal - CVE-2021-36156 Bypass
Medium 5.3
In plain English
A medium-severity path traversal in Loki from Grafana. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.4%top 64.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/grafana/loki | no fix listed | GO-2026-5115 |
| Go | github.com/grafana/loki/v3 | 3.6.4 | GHSA-497x-rrr9-68jp |
| Go | github.com/grafana/loki/v3 | 3.6.4 | GO-2026-5115 |
Affected products (as reported)
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
References
- https://grafana.com/security/security-advisories/cve-2026-21726 vendor-advisory