Vulnerability record · CVE-2026-77763 · published 21 August 2026
CVE-2026-77763: Path traversal vulnerability
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.
Description
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.
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:
References
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Related vulnerabilities
Same products first, then exploited flaws of the same weakness class.
Source: NIST National Vulnerability Database (record CVE-2026-77763), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.
