{"id":"CVE-2026-21726","aliases":["GHSA-497x-rrr9-68jp","GO-2026-5115"],"url":"https://o3.security/vulnerability/CVE-2026-21726","summary":"Loki Path Traversal - CVE-2021-36156 Bypass","details":"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}\n\nThanks to Prasanth Sundararajan for reporting this vulnerability.","published":"2026-04-15T19:24:31.268Z","modified":"2026-08-28T11:30:32.497823580Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"},"epss":{"score":0.00409,"percentile":0.33893,"asOf":"2026-08-12"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/grafana/loki/v3","fixedVersion":"3.6.4"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21726.json"},{"type":"ADVISORY","url":"https://grafana.com/security/security-advisories/cve-2026-21726"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21726"},{"type":"PACKAGE","url":"https://github.com/grafana/loki"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-28T11:30:32.497823580Z"}}