{"dataType": "CVE_RECORD", "dataVersion": "5.1", "cveMetadata": {"cveId": "CVE-2025-20271", "assignerOrgId": "d1c1063e-7a18-46af-9102-31f8928bc633", "state": "PUBLISHED", "assignerShortName": "cisco", "dateReserved": "2024-10-10T19:15:13.245Z", "datePublished": "2025-06-18T16:38:00.686Z", "dateUpdated": "2025-06-18T17:58:55.159Z"}, "containers": {"cna": {"title": "Cisco Meraki MX and Z Series AnyConnect VPN with Client Certificate Authentication Denial of Service Vulnerability", "metrics": [{"format": "cvssV3_1", "cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H", "baseScore": 8.6, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}}], "descriptions": [{"lang": "en", "value": "A vulnerability in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series Teleworker Gateway devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the Cisco AnyConnect service on an affected device.\r\n\r\nThis vulnerability is due to variable initialization errors when an SSL VPN session is established. An attacker could exploit this vulnerability by sending a sequence of crafted HTTPS requests to an affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to restart, resulting in the failure of all established SSL VPN sessions and forcing remote users to initiate a new VPN connection and re-authenticate. A sustained attack could prevent new SSL VPN connections from being established, effectively making the Cisco AnyConnect VPN service unavailable for all legitimate users."}], "references": [{"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-meraki-mx-vpn-dos-sM5GCfm7", "name": "cisco-sa-meraki-mx-vpn-dos-sM5GCfm7"}], "exploits": [{"lang": "en", "value": "The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory."}], "source": {"advisory": "cisco-sa-meraki-mx-vpn-dos-sM5GCfm7", "discovery": "EXTERNAL", "defects": ["CSCwo79255"]}, "problemTypes": [{"descriptions": [{"lang": "en", "description": "Use of Uninitialized Variable", "type": "cwe", "cweId": "CWE-457"}]}], "affected": [{"vendor": "Cisco", "product": "Cisco Meraki MX Firmware", "versions": [{"version": "N/A", "status": "affected"}]}], "providerMetadata": {"orgId": "d1c1063e-7a18-46af-9102-31f8928bc633", "shortName": "cisco", "dateUpdated": "2025-06-18T16:38:00.686Z"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2025-06-18T17:56:26.880823Z", "id": "CVE-2025-20271", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-06-18T17:58:55.159Z"}}]}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "A vulnerability in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series Teleworker Gateway devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the Cisco AnyConnect service on an affected device.\r\n\r\nThis vulnerability is due to variable initialization errors when an SSL VPN session is established. An attacker could exploit this vulnerability by sending a sequence of crafted HTTPS requests to an affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to restart, resulting in the failure of all established SSL VPN sessions and forcing remote users to initiate a new VPN connection and re-authenticate. A sustained attack could prevent new SSL VPN connections from being established, effectively making the Cisco AnyConnect VPN service unavailable for all legitimate users."}, {"lang": "es", "value": "Una vulnerabilidad en el servidor VPN Cisco AnyConnect de los dispositivos Cisco Meraki MX y Cisco Meraki Z Series Teleworker Gateway podr\u00eda permitir que un atacante remoto no autenticado provoque una denegaci\u00f3n de servicio (DoS) en el servicio Cisco AnyConnect de un dispositivo afectado. Esta vulnerabilidad se debe a errores de inicializaci\u00f3n variables al establecer una sesi\u00f3n VPN SSL. Un atacante podr\u00eda explotar esta vulnerabilidad enviando una secuencia de solicitudes HTTPS manipuladas a un dispositivo afectado. Una explotaci\u00f3n exitosa podr\u00eda permitir al atacante reiniciar el servidor VPN Cisco AnyConnect, lo que provocar\u00eda el fallo de todas las sesiones VPN SSL establecidas y obligar\u00eda a los usuarios remotos a iniciar una nueva conexi\u00f3n VPN y a autenticarse de nuevo. Un ataque continuo podr\u00eda impedir el establecimiento de nuevas conexiones VPN SSL, lo que har\u00eda que el servicio VPN Cisco AnyConnect no estuviera disponible para todos los usuarios leg\u00edtimos."}], "id": "CVE-2025-20271", "lastModified": "2025-06-23T20:16:59.783", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.6, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 4.0, "source": "psirt@cisco.com", "type": "Primary"}]}, "published": "2025-06-18T17:15:29.053", "references": [{"source": "psirt@cisco.com", "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-meraki-mx-vpn-dos-sM5GCfm7"}], "sourceIdentifier": "psirt@cisco.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-457"}], "source": "psirt@cisco.com", "type": "Primary"}]}

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