PT-2026-55092 · Go · Goshs.De/Goshs/V2

Published

2026-07-01

·

Updated

2026-07-01

CVSS v3.1

8.1

High

VectorAV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

WebDAV listener ignores --read-only, --upload-only, and --no-delete mode flags

Ecosystem: Go Package: goshs.de/goshs/v2 (github.com/patrickhener/goshs) Affected: <= v2.0.9 (every release that ships the WebDAV handler)

Summary

When goshs is launched with WebDAV enabled (-w), the mode-restriction flags --read-only, --upload-only, and --no-delete are enforced only on the primary HTTP port. The WebDAV port is wired straight to golang.org/x/net/webdav.Handler with no equivalent guard, so an authenticated WebDAV client can PUT, DELETE, MKCOL, MOVE, and COPY despite the operator's stated intent.

Details

httpserver/server.go:207-238 — the WebDAV mux registers only IPWhitelistMiddleware, ServerHeaderMiddleware, and optionally BasicAuthMiddleware. There is no fs.ReadOnly || fs.UploadOnly || fs.NoDelete check on the WebDAV path. The HTTP mux in the same file (lines 134-204) does check these flags on every state-changing route.

Proof of concept

bash
mkdir -p /tmp/r && echo secret > /tmp/r/x.txt
goshs -p 18000 -wp 18001 -w -ro -d /tmp/r -b admin:pw &

curl -u admin:pw -X PUT  http://localhost:18000/y.txt --data x  # 403 (HTTP enforces -ro)
curl -u admin:pw -X PUT  http://localhost:18001/y.txt --data x  # 201 (WebDAV writes anyway)
curl -u admin:pw -X DELETE http://localhost:18001/x.txt      # 204 (WebDAV deletes anyway)
curl -u admin:pw -X MKCOL http://localhost:18001/pwned/      # 201 (WebDAV creates dir)

Impact

  • Integrity — --read-only and --no-delete are silently downgraded to "no protection" on the WebDAV port. Any WebDAV client (curl, cadaver, Windows Explorer, Finder) can overwrite/delete files.
  • Confidentiality — --upload-only is also bypassed: WebDAV GET/PROPFIND still return file contents.
  • Trust — operators using goshs -w -ro -d /srv/case-files -b reviewer:pw to deliver engagement artifacts believe the directory is immutable. It isn't.

Suggested fix

Add a small http.HandlerFunc in front of wdHandler that maps WebDAV verbs to the existing mode flags:
go
wdGuard := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  switch r.Method {
  case http.MethodPut, "MKCOL", "MOVE", "COPY":
    if fs.ReadOnly || fs.UploadOnly { http.Error(w, "read-only", 403); return }
  case http.MethodDelete:
    if fs.ReadOnly || fs.UploadOnly || fs.NoDelete { http.Error(w, "delete disabled", 403); return }
  case http.MethodGet, "PROPFIND", "HEAD":
    if fs.UploadOnly { http.Error(w, "upload-only", 403); return }
  }
  wdHandler.ServeHTTP(w, r)
})
Add regression tests in integration/functions.go covering each mode flag × each WebDAV verb.
Reporter: Nishant Verma. Reproduced live against goshs v2.0.9 (commit 8fc1e91) on 2026-05-27.

Fix

Improper Access Control

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Weakness Enumeration

CWE-284

Related Identifiers

GHSA-3WHC-QVHV-XQJP

Affected Products

Goshs.De/Goshs/V2