GHSA-3whc-qvhv-xqjp

# 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`](https://github.com/patrickhener/goshs/blob/v2.0.9/httpserver/server.go#L207-L238) — 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.