CVE-2026-77763

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. High risk of data tampering.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-08-21 11:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-16 15:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.5% in the next 30 days (EPSS).
• Severity: 7.1 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-08-21 11:17 UTC

Last modified

2026-10-16 15:10 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Deferred

Attack profile CVSS 4.0 · 7.1

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

Passive

Confidentiality

None

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-77763.md and follow it. Check whether this project is affected by CVE-2026-77763. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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