{"id":"CVE-2026-77763","summary":"JuiceFS Local Filestore Backend Joins Object Keys onto the Storage Root Without a Containment Check, Allowing Writes Outside the Configured Directory","details":"The filestore backend in pkg/object/file.go, used for file:// stores and as a common juicefs sync destination, derived every operation's target from path(key), which returned either filepath.Join(d.root, key) or filepath.Clean(d.root + key) with no check that the result stayed beneath the root. Put, Get, Head, Delete, Chmod, Chown, Symlink and Readlink all consumed that value directly. Object keys enumerated from a source object store during a sync are not constrained the way local filesystem names are, so a key containing traversal segments causes juicefs to write attacker-supplied content to a path outside the intended local destination, and no error is returned. An operator syncing from a bucket whose contents they do not fully control, such as a shared or public bucket or one an attacker can write to, is therefore exposed to a file write at an attacker-influenced location. The fix changes path() to return an error and rejects any key whose resolved path escapes the root.","modified":"2026-08-23T03:53:42.284405870Z","published":"2026-08-21T11:05:13.650Z","database_specific":{"cna_assigner":"VulnCheck","cwe_ids":["CWE-22"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77763.json"},"references":[{"type":"WEB","url":"https://proxy.golang.org"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77763.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77763"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/juicefs-local-filestore-backend-joins-object-keys-onto-the-storage-root-without-a-containment-check-allowing-writes-outside-the-configured-directory"},{"type":"REPORT","url":"https://github.com/juicedata/juicefs/issues/7401"},{"type":"REPORT","url":"https://github.com/juicedata/juicefs/pull/7425"},{"type":"FIX","url":"https://github.com/juicedata/juicefs/commit/0bcd70b3d13088d38127d6fb5750c91be7c4ec16"},{"type":"PACKAGE","url":"https://github.com/juicedata/juicefs"},{"type":"ARTICLE","url":"https://github.com/juicedata/juicefs/blob/v1.4.1/pkg/object/file.go"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/juicedata/juicefs","events":[{"introduced":"0"},{"fixed":"0bcd70b3d13088d38127d6fb5750c91be7c4ec16"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"last_affected":"1.4.1"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v1.4.0-dev","v1.3.0-beta2","v1.3.0-dev","v1.2.0-dev","v0.13.1","v0.13.0","v0.12.1","v0.12.0","v0.11.0","v0.10.0","v0.9.3","v0.9.2","v0.9.1","v0.9.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77763.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}]}