---
id: CVE-2026-58371
title: >-
  SeaweedFS < 4.30 - Cross-Origin Information Disclosure via Unvalidated JSONP
  callback Parameter
summary: >-
  SeaweedFS before 4.30 reflects the callback query parameter verbatim into
  responses served with Content-Type application/javascript in the shared
  writeJson helper (weed/server/common.go), with no callback-name validation, no
  X-Content-Ty…
severity: low
cvss: 3.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-79
vendor: seaweedfs
product: seaweedfs
affected:
  - seaweedfs < 4.30
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-07-01T15:05:44.800911Z'
exploitAvailable: true
published: '2026-06-30'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T14:06:56.821Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-58371'
references:
  - url: 'https://github.com/seaweedfs/seaweedfs/releases/tag/4.30'
    label: seaweedfs 4.30 Release Notes
  - url: 'https://github.com/seaweedfs/seaweedfs/pull/9686'
    label: Fix PR
  - url: >-
      https://github.com/seaweedfs/seaweedfs/commit/77dcb20a7485074d37340985d53103f94538abe6
    label: Patch Commit
  - url: 'https://github.com/geo-chen/oss/blob/main/seaweedfs.md'
    label: Researcher Disclosure
  - url: >-
      https://www.vulncheck.com/advisories/seaweedfs-cross-origin-information-disclosure-via-unvalidated-jsonp-callback-parameter
tags:
  - cve.org
  - exploit-available
epss: 0.00333
epssPercentile: 0.26659
ingestedAt: '2026-11-08T14:51:22.299Z'
---

## Overview

SeaweedFS before 4.30 reflects the callback query parameter verbatim into responses served with Content-Type application/javascript in the shared writeJson helper (weed/server/common.go), with no callback-name validation, no X-Content-Type-Options: nosniff header, and no CORS allow-list. Every JSON endpoint that uses writeJson - including the unauthenticated master endpoints /dir/status, /dir/lookup and /cluster/status, the volume server /status, and the filer directory listing, all reachable in the default configuration (no -whiteList, no security.toml, bound to 0.0.0.0) - can therefore be loaded cross-origin via a script tag with a chosen callback, letting a third-party web page read cluster topology, volume server URLs and gRPC ports, file identifiers, and directory listings. Because the callback string is reflected at the start of the body and no nosniff header is sent, MIME-sniffing clients may also interpret the reflected content as HTML.

## Affected

- `seaweedfs < 4.30`

## Remediation

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