---
id: CVE-2026-77368
title: SeaweedFS is a distributed storage system for files and blobs
summary: >-
  SeaweedFS is a distributed storage system for files and blobs. In version
  4.39, the filer's TUS resumable-upload handler checks JWT allowed_prefixes
  scoping only when a session is created, letting a low-privilege tenant hijack
  another te…
severity: high
cvss: 7.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:L'
cwe:
  - CWE-639
published: '2026-08-26'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:09:13.080'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77368'
references:
  - url: >-
      https://github.com/seaweedfs/seaweedfs/commit/ce82e3a057080162a9fba11889157d2255815f71
    label: security-advisories@github.com
  - url: >-
      https://github.com/seaweedfs/seaweedfs/commit/fa549e9c83b7799d512157d728f52052912831af
    label: security-advisories@github.com
  - url: >-
      https://github.com/seaweedfs/seaweedfs/security/advisories/GHSA-99q7-x53r-6j4g
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00215
epssPercentile: 0.12214
ingestedAt: '2026-09-09T21:22:45.557Z'
---

## Overview

SeaweedFS is a distributed storage system for files and blobs. In version 4.39, the filer's TUS resumable-upload handler checks JWT allowed_prefixes scoping only when a session is created, letting a low-privilege tenant hijack another tenant's upload session to write content to filer paths their own token forbids. The HEAD, PATCH, and DELETE verbs that act on an existing session by its id never verify that the session's stored target path falls within the caller's allowed prefixes, so a tenant who obtains another upload's session identifier can PATCH attacker bytes into it and, on completion, have the file land at the victim's out-of-scope path. The same token can also DELETE other tenants' sessions and HEAD them to read upload progress and size, defeating the JWT prefix isolation. This vulnerability only affects deployments that configure filer JWT signing and have TUS uploads enabled. This issue is fixed in version 4.40.

## Remediation

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