{"answers":{"affected":"4 open source packages ship an affected version, including github.com/grafana/loki/v3 and github.com/grafana/loki. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-21726 in the wild and no public exploit code.","fix":"Upgrade github.com/grafana/loki/v3 to 3.6.4 or later.","what":"CVE-2026-21726 is a medium-severity path traversal vulnerability in Grafana Loki, published on 15 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-21726 and fix it if it is affected.\n\nWhat it is: CVE-2026-21726 is a medium-severity path traversal vulnerability in Grafana Loki, published on 15 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-21726 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/grafana/loki/v3 (Go): affected all versions; fixed in 3.6.4\n- github.com/grafana/loki/v3 (Go): affected all versions; fixed in 3.6.4\n- github.com/grafana/loki/v3 (Go): affected all versions; fixed in 3.6.4\n- github.com/grafana/loki (Go): affected all versions; no fix listed\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-21726/ (Markdown: https://insights.sbomify.com/CVE-2026-21726/index.md)","id":"CVE-2026-21726","markdown":"https://insights.sbomify.com/CVE-2026-21726/index.md","name":"CVE-2026-21726","record":{"aliases":["CLEANSTART-2026-JO14647","CLEANSTART-2026-WN62977","CLEANSTART-2026-YM30518","CLEANSTART-2026-ZS27491","ECHO-d86c-cc77-aee6","GHSA-497x-rrr9-68jp","GO-2026-5115","MINI-2hgx-gh8q-r66m","MINI-3376-m49q-82jj","MINI-3wgj-6m78-mpf8","MINI-43q4-qxwp-6qpj","MINI-5hwp-xm7h-33rf","MINI-5p5x-gmq6-49x6","MINI-8gv7-pqm7-mx42","MINI-9cjh-8h5h-6r8p","MINI-9v53-pwqr-pj2w","MINI-9xj5-w7rv-r3qg","MINI-cc95-64vw-32m8","MINI-ccpr-458h-wh3j","MINI-cqcr-qgp9-5wpc","MINI-ff7w-qg8c-jc9x","MINI-g29c-7xwp-5hhw","MINI-gxrj-9mrw-r8cm","MINI-h8xp-3pvj-q6mf","MINI-m2cj-h79x-rhgc","MINI-qffh-4xvv-h66q","MINI-qfm4-fp5v-2m77","MINI-qpcp-5x47-qh4g","MINI-v89m-7wq7-f559","MINI-vf2w-f8gp-2xw9","MINI-w66g-855v-4f99","MINI-wfgh-wchv-f2fg","MINI-x268-59h8-8693","MINI-x63h-rc69-r3hq"],"analysis":{"component_type":"server_software","fix_type":"patch","impacts":["data_read"],"network_reachable":"yes","non_default_config":false,"product_category":"Grafana Loki","requires_auth":"none","summary":"Attackers can bypass path traversal protections in Grafana Loki to read arbitrary files via the Ruler API endpoint.","user_interaction":"not_required","vuln_class":"path_traversal"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GRAFANA","cpe":[{"product":"loki","vendor":"grafana"}],"cvss":{"score":5.3,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"},"cwes":[{"id":"CWE-22","name":"Improper Limitation of a Pathname to a Restricted Directory"}],"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}\n\nThanks to Prasanth Sundararajan for reporting this vulnerability.","ecosystems":["Go"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"Loki Path Traversal - CVE-2021-36156 Bypass","id":"CVE-2026-21726","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Go","product":null,"products":[],"type":"path_traversal","year":"2026"},"n_packages":4,"n_references":1,"next":{"headline":"Grafana Correlations: Cross-Tenant Data Disclosure and Permanent Deletion via Legacy org_id=0 Record","id":"CVE-2026-21727"},"packages":[{"ecosystem":"Go","fixed":[],"introduced":["0"],"last_affected":[],"package":"github.com/grafana/loki","purl":"pkg:golang/github.com/grafana/loki","source":"GO-2026-5115"},{"ecosystem":"Go","fixed":["3.6.4"],"introduced":["0"],"last_affected":[],"package":"github.com/grafana/loki/v3","purl":null,"source":"GHSA-497x-rrr9-68jp"},{"ecosystem":"Go","fixed":["3.6.4"],"introduced":["0"],"last_affected":[],"package":"github.com/grafana/loki/v3","purl":"pkg:golang/github.com/grafana/loki/v3","source":"GHSA-497x-rrr9-68jp"},{"ecosystem":"Go","fixed":["3.6.4"],"introduced":["0"],"last_affected":[],"package":"github.com/grafana/loki/v3","purl":"pkg:golang/github.com/grafana/loki/v3","source":"GO-2026-5115"}],"prev":{"headline":"Authorization Bypass via TOCTOU in Grafana Datasource Deletion by Name","id":"CVE-2026-21725"},"products":["Loki"],"published":"2026-04-15","related":[{"cvss_score":5.3,"headline":"Path traversal in Grafana Loki","id":"CVE-2021-36156","kev_date_added":null,"published":"2021-08-03"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CC BY 4.0","name":"Go Vulnerability Database","prefix":"GO"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-08-27","vendors":["Grafana"]},"summary":"Attackers can bypass path traversal protections in Grafana Loki to read arbitrary files via the Ruler API endpoint.","url":"https://insights.sbomify.com/CVE-2026-21726/"}