# CVE-2026-77763: Path traversal in juicefs

> Attacker-controlled object keys during sync can write files outside the configured storage root, allowing arbitrary file modification.

- **Severity:** High 7.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 21 Aug 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-2pgv-c2r7-f43r

## What is CVE-2026-77763?

CVE-2026-77763 is a high-severity path traversal vulnerability in juicedata juicefs, published on 21 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-77763?


## How do I fix CVE-2026-77763?

No fix has been published for CVE-2026-77763 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-77763 being exploited?

There is no known exploitation of CVE-2026-77763 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77763 and fix it if it is affected.

What it is: CVE-2026-77763 is a high-severity path traversal vulnerability in juicedata juicefs, published on 21 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-77763 in the wild and no public exploit code.

Affected product: juicedata juicefs. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. 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.
2. 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.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-77763/ (Markdown: https://insights.sbomify.com/CVE-2026-77763/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77763
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77763
- OSV: https://osv.dev/vulnerability/CVE-2026-77763

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77763/
Summaries are generated and may contain mistakes; the official description above is the record.