CVE-2026-21726

EUVD-2026-23100
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.
Path Traversal
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 4%
Affected Products (NVD)
VendorProductVersion
grafanaloki
𝑥
< 3.6.4
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://grafana.com/security/security-advisories/cve-2026-21726