george0papasotiriou/cve-2026-11116-snmpv3-authentication-bypass-via-default-engineidDemonstrates CVE-2026-11116 SNMPv3 authentication bypass caused by guessable default EngineIDs, with a Python pysnmp simulation and guidance for detecting and understanding the attack.
# snmp_agent_sim.py - SNMPv3 agent using well-known EngineID
from pysnmp.hlapi import *
def snmp_get(engine_id=SnmpEngineID(hexValue='8000000001020304')):
iterator = getCmd(
SnmpEngine(engineID=engine_id),
CommunityData('public', mpModel=0), # not v3, but demo
UdpTransportTarget(('localhost', 161)),
ContextData(),
ObjectType(ObjectIdentity('SNMPv2-MIB', 'sysDescr', 0))
)
errorIndication, errorStatus, errorIndex, varBinds = next(iterator)
print(varBinds)
# Vulnerability: EngineID is guessable; attacker can compute authentication keys offline.
print("SNMPv3 with default EngineID vulnerable to key derivation attacks.")
An SNMPv3 device uses a well‑known or easily guessable EngineID (e.g., all zeros or derived from MAC address). An attacker can pre‑compute authentication and privacy keys, bypassing SNMPv3 security and gaining read/write access to the device.
The simulation prints a warning; a real attack involves sniffing the EngineID and brute‑forcing or using default passwords. Run:
pip install pysnmp
python snmp_agent_sim.py