EUVD-2026-308576

fkie_cve-2026-42091

goshs is a SimpleHTTPServer written in Go. Prior to version 2.0.2, the PUT upload handler (httpserver/updown.go) lacks the CSRF token validation that was added to the POST upload handler during the CVE-2026-40883 fix. Combined with the unconditional Access-Control-Allow-Origin: * on the OPTIONS preflight handler (httpserver/server.go), any website can write arbitrary files to a goshs instance through the victim's browser — bypassing network isolation (e.g. localhost, internal network). This issue has been patched in version 2.0.2.

GHSA-rhf7-wvw3-vjvm — goshs has Cross-Origin Arbitrary File Write via Missing CSRF on PUT and Wildcard CORS

Affected: Go: github.com/patrickhener/goshs/v2, Go: github.com/patrickhener/goshs

### Summary The PUT upload handler (`httpserver/updown.go`) lacks the CSRF token validation that was added to the POST upload handler during the GHSA-jrq5-hg6x-j6g3 fix. Combined with the unconditional `Access-Control-Allow-Origin: *` on the OPTIONS preflight handler (`httpserver/server.go`), any website can write arbitrary files to a goshs instance through the victim's browser — bypassing network isolation (e.g. localhost, internal network).

### Details **Root Cause 1 — Missing CSRF on PUT** (`httpserver/updown.go:19`)

When GHSA-jrq5-hg6x-j6g3 was fixed (commit `e3c3d37`), `checkCSRF()` was added to the POST `upload()` function (line 78) but not to the PUT `put()` function directly above it in the same file. This means PUT requests are accepted without any CSRF token.

```go // POST — protected func (fs *FileServer) upload(w http.ResponseWriter, req *http.Request) { if !fs.checkCSRF(w, req) { return } // ... }

// PUT — unprotected func (fs *FileServer) put(w http.ResponseWriter, req *http.Request) { // No checkCSRF call // ... } ```

**Root Cause 2 — Wildcard CORS** (`httpserver/server.go:126`)

The OPTIONS handler unconditionally returns permissive CORS headers:

```go w.Header().Set("Access-Control-Allow-Origin", "*") w.Header().Set("Access-Control-Allow-Methods", "POST, PUT, OPTIONS") w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization") ```

This allows any website's JavaScript to pass the browser's CORS preflight check and s…

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EUVD-2026-308576

fkie_cve-2026-42091

GHSA-rhf7-wvw3-vjvm — goshs has Cross-Origin Arbitrary File Write via Missing CSRF on PUT and Wildcard CORS