CVE-2026-3547

# PoC for CVE-2026-3547 (Conceptual) # This script demonstrates sending a malformed TLS ClientHello # with a crafted ALPN extension to trigger the OOB read. import socket import struct def create_malformed_client_hello(): # Simplified TLS Record Layer # Content Type: Handshake (0x16) # Version: TLS 1.2 (0x0303) # Length: Placeholder # Handshake Protocol # Type: ClientHello (0x01) # Length: Placeholder # Version: TLS 1.2 (0x0303) # Random: 32 bytes (zeros for demo) # Session ID: Length 0 # Cipher Suites: Length 2, Suite 0x009C (TLS_RSA_WITH_AES_128_GCM_SHA256) # Extensions # ALPN Extension Type: 0x0010 # ALPN Extension Length: Malformed # ALPN List Length: Large value to trigger OOB # Note: Actual exploitation requires precise packet crafting. # This is a structural representation. pass # Target IP and Port target_host = '192.168.1.1' target_port = 443 try: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((target_host, target_port)) # send(create_malformed_client_hello()) s.close() print("Packet sent.") except Exception as e: print(f"Error: {e}")

{"cve": {"id": "CVE-2026-3547", "sourceIdentifier": "[email protected]", "published": "2026-03-19T21:17:12.653", "lastModified": "2026-03-26T18:27:31.467", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Out-of-bounds read in ALPN parsing due to incomplete validation. wolfSSL 5.8.4 and earlier contained an out-of-bounds read in ALPN handling when built with ALPN enabled (HAVE_ALPN / --enable-alpn). A crafted ALPN protocol list could trigger an out-of-bounds read, leading to a potential process crash (denial of service). Note that ALPN is disabled by default, but is enabled for these 3rd party compatibility features: enable-apachehttpd, enable-bind, enable-curl, enable-haproxy, enable-hitch, enable-lighty, enable-jni, enable-nginx, enable-quic."}, {"lang": "es", "value": "Lectura fuera de límites en el análisis de ALPN debido a una validación incompleta. wolfSSL 5.8.4 y versiones anteriores contenían una lectura fuera de límites en el manejo de ALPN cuando se compilaba con ALPN habilitado (HAVE_ALPN / --enable-alpn). Una lista de protocolos ALPN manipulada podría desencadenar una lectura fuera de límites, lo que podría llevar a un bloqueo potencial del proceso (denegación de servicio). Tenga en cuenta que ALPN está deshabilitado por defecto, pero está habilitado para estas características de compatibilidad de terceros: enable-apachehttpd, enable-bind, enable-curl, enable-haproxy, enable-hitch, enable-lighty, enable-jni, enable-nginx, enable-quic."}], "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": "Secondary", "description": [{"lang": "en", "value": "CWE-125"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.9.0", "matchCriteriaId": "DA3FA1CB-CEDC-4D49-9ECD-99BBF1602312"}]}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssl/pull/9859", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}]}}