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
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Grafana | Loki | 2.3.0 – < 3.5.9 | 3.5.9 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | govulncheck-vulndb | 0.0.20260723T184607-160000.1.1 | openSUSE-SU-2026:21483-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | grafana-12.3 | 12.3.7-r0 | — |
| Wolfi rolling | grafana-12.4 | 12.4.4-r0 | — |
| Wolfi rolling | grafana-13.0 | 13.0.2-r0 | — |
| Wolfi rolling | grafana-alloy | 1.15.1-r2 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/grafana/loki | all versions | — | GO-2026-5115 |
| Go | github.com/grafana/loki/v3 | < 3.6.4 | 3.6.4 | GHSA-497x-rrr9-68jp |
Advisories 2
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- WID-SEC-2026-0242 Grafana Loki: Schwachstelle ermöglicht Offenlegung von Informationen BSI CERT-Bund (WID) · Apr 15, 2026
References
- https://grafana.com/security/security-advisories/cve-2026-21726 vendor-advisory