---
id: CVE-2026-77763
title: >-
  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 + k…
summary: >-
  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 + k…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N'
cwe:
  - CWE-22
vendor: juicedata
product: github.com/juicedata/juicefs
affected:
  - github.com/juicedata/juicefs <= 1.4.1
published: '2026-08-21'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T20:43:32.537'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77763'
references:
  - url: 'https://github.com/juicedata/juicefs'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/juicedata/juicefs/blob/v1.4.1/pkg/object/file.go'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/juicedata/juicefs/commit/0bcd70b3d13088d38127d6fb5750c91be7c4ec16
    label: disclosure@vulncheck.com
  - url: 'https://github.com/juicedata/juicefs/issues/7401'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/juicedata/juicefs/pull/7425'
    label: disclosure@vulncheck.com
  - 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
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
epss: 0.00498
epssPercentile: 0.4001
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-08-21T21:32:48.194454Z'
ingestedAt: '2026-09-24T15:45:56.699Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.