{"containers": {"cna": {"affected": [{"product": "NAS326", "vendor": "ZyXEL", "versions": [{"lessThanOrEqual": "V5.21(AAZF.7)C0", "status": "affected", "version": "V5.21(AAZF.7)C0", "versionType": "custom"}]}, {"product": "NAS520", "vendor": "ZyXEL", "versions": [{"lessThanOrEqual": "V5.21(AASZ.3)C0", "status": "affected", "version": "V5.21(AASZ.3)C0", "versionType": "custom"}]}, {"product": "NAS540", "vendor": "ZyXEL", "versions": [{"lessThanOrEqual": "V5.21(AATB.4)C0", "status": "affected", "version": "V5.21(AATB.4)C0", "versionType": "custom"}]}, {"product": "NAS542", "vendor": "ZyXEL", "versions": [{"lessThanOrEqual": "V5.21(ABAG.4)C0", "status": "affected", "version": "V5.21(ABAG.4)C0", "versionType": "custom"}]}, {"product": "NSA210", "vendor": "ZyXEL", "versions": [{"status": "affected", "version": "all"}]}, {"product": "NSA220", "vendor": "ZyXEL", "versions": [{"status": "affected", "version": "all"}]}, {"product": "NSA220+", "vendor": "ZyXEL", "versions": [{"status": "affected", "version": "all"}]}, {"product": "NSA221", "vendor": "ZyXEL", "versions": [{"status": "affected", "version": "all"}]}, {"product": "NSA310", "vendor": "ZyXEL", "versions": [{"lessThanOrEqual": "V4.75(AALH.2)C0", "status": "affected", "version": "V4.75(AALH.2)C0", "versionType": "custom"}]}, {"product": "NSA320", "vendor": "ZyXEL", "versions": [{"status": "affected", "version": "all"}]}, {"product": "NSA320S", "vendor": "ZyXEL", "versions": [{"lessThanOrEqual": "V4.75(AANV.2)C0", "status": "affected", "version": "V4.75(AANV.2)C0", "versionType": "custom"}]}, {"product": "NSA325", "vendor": "ZyXEL", "versions": [{"lessThanOrEqual": "V4.81(AAAJ.1)C0", "status": "affected", "version": "V4.81(AAAJ.1)C0", "versionType": "custom"}]}, {"product": "NSA325v2", "vendor": "ZyXEL", "versions": [{"lessThanOrEqual": "V4.81(AALS.1)C0", "status": "affected", "version": "V4.81(AALS.1)C0", "versionType": "custom"}]}], "credits": [{"lang": "en", "value": "Thanks to Alex Holden of Hold Security for finding and reporting this vulnerability."}], "datePublic": "2020-02-20T00:00:00.000Z", "descriptions": [{"lang": "en", "value": "Multiple ZyXEL network-attached storage (NAS) devices running firmware version 5.21 contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable device. 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If the username parameter contains certain characters, it can allow command injection with the privileges of the web server that runs on the ZyXEL device. Although the web server does not run as the root user, ZyXEL devices include a setuid utility that can be leveraged to run any command with root privileges. As such, it should be assumed that exploitation of this vulnerability can lead to remote code execution with root privileges. By sending a specially-crafted HTTP POST or GET request to a vulnerable ZyXEL device, a remote, unauthenticated attacker may be able to execute arbitrary code on the device. This may happen by directly connecting to a device if it is directly exposed to an attacker. However, there are ways to trigger such crafted requests even if an attacker does not have direct connectivity to a vulnerable devices. For example, simply visiting a website can result in the compromise of any ZyXEL device that is reachable from the client system. Affected products include: NAS326 before firmware V5.21(AAZF.7)C0 NAS520 before firmware V5.21(AASZ.3)C0 NAS540 before firmware V5.21(AATB.4)C0 NAS542 before firmware V5.21(ABAG.4)C0 ZyXEL has made firmware updates available for NAS326, NAS520, NAS540, and NAS542 devices. Affected models that are end-of-support: NSA210, NSA220, NSA220+, NSA221, NSA310, NSA310S, NSA320, NSA320S, NSA325 and NSA325v2"}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-78", "description": "CWE-78 OS Command Injection"}]}], "providerMetadata": {"orgId": "37e5125f-f79b-445b-8fad-9564f167944b", "shortName": "certcc", "dateUpdated": "2020-03-04T19:30:18.000Z"}, "x_legacyV4Record": {"credit": [{"lang": "eng", "value": "Thanks to Alex Holden of Hold Security for finding and reporting this vulnerability."}], "source": {"discovery": "UNKNOWN"}, "affects": {"vendor": {"vendor_data": [{"product": {"product_data": [{"version": {"version_data": [{"version_name": "V5.21(AAZF.7)C0", "version_value": "V5.21(AAZF.7)C0", "version_affected": "<="}]}, "product_name": "NAS326"}, {"version": {"version_data": [{"version_name": "V5.21(AASZ.3)C0", "version_value": "V5.21(AASZ.3)C0", "version_affected": "<="}]}, "product_name": "NAS520"}, {"version": {"version_data": [{"version_name": "V5.21(AATB.4)C0", "version_value": "V5.21(AATB.4)C0", "version_affected": "<="}]}, "product_name": "NAS540"}, {"version": {"version_data": [{"version_name": "V5.21(ABAG.4)C0", "version_value": "V5.21(ABAG.4)C0", "version_affected": "<="}]}, "product_name": "NAS542"}, {"version": {"version_data": [{"version_value": "all", "version_affected": "="}]}, "product_name": "NSA210"}, {"version": {"version_data": [{"version_value": "all", "version_affected": "="}]}, "product_name": "NSA220"}, {"version": {"version_data": [{"version_value": "all", "version_affected": "="}]}, "product_name": "NSA220+"}, {"version": {"version_data": [{"version_value": "all", "version_affected": "="}]}, "product_name": "NSA221"}, {"version": {"version_data": [{"version_name": "V4.75(AALH.2)C0", "version_value": "V4.75(AALH.2)C0", "version_affected": "<="}]}, "product_name": "NSA310"}, {"version": {"version_data": [{"version_value": "all", "version_affected": "="}]}, "product_name": "NSA320"}, {"version": {"version_data": [{"version_name": "V4.75(AANV.2)C0", "version_value": "V4.75(AANV.2)C0", "version_affected": "<="}]}, "product_name": "NSA320S"}, {"version": {"version_data": [{"version_name": "V4.81(AAAJ.1)C0", "version_value": "V4.81(AAAJ.1)C0", "version_affected": "<="}]}, "product_name": "NSA325"}, {"version": {"version_data": [{"version_name": "V4.81(AALS.1)C0", "version_value": "V4.81(AALS.1)C0", "version_affected": "<="}]}, "product_name": "NSA325v2"}]}, "vendor_name": "ZyXEL"}]}}, "exploit": [{"lang": "en", "value": "https://kb.cert.org/artifacts/cve-2020-9054.html"}], "solution": [{"lang": "en", "value": "ZyXEL has made firmware updates available for NAS326, NAS520, NAS540, NAS542, ATP100, ATP200, ATP500, ATP800, USG20-VPN, USG20W-VPN, USG40, USG40W, USG60, USG60W, USG110, USG210, USG310, USG1100, USG1900, USG2200, VPN50, VPN100, VPN300, VPN1000, ZyWALL110, ZyWALL310, and ZyWALL1100 devices."}], "data_type": "CVE", "generator": {"engine": "Vulnogram 0.0.9"}, "references": {"reference_data": [{"url": "https://cwe.mitre.org/data/definitions/78.html", "name": "https://cwe.mitre.org/data/definitions/78.html", "refsource": "MISC"}, {"url": "https://www.zyxel.com/support/remote-code-execution-vulnerability-of-NAS-products.shtml", "name": "https://www.zyxel.com/support/remote-code-execution-vulnerability-of-NAS-products.shtml", "refsource": "CONFIRM"}, {"url": "https://kb.cert.org/vuls/id/498544/", "name": "VU#498544", "refsource": "CERT-VN"}, {"url": "https://kb.cert.org/artifacts/cve-2020-9054.html", "name": "https://kb.cert.org/artifacts/cve-2020-9054.html", "refsource": "MISC"}, {"url": "https://krebsonsecurity.com/2020/02/zyxel-fixes-0day-in-network-storage-devices/", "name": "https://krebsonsecurity.com/2020/02/zyxel-fixes-0day-in-network-storage-devices/", "refsource": "MISC"}]}, "data_format": "MITRE", "description": {"description_data": [{"lang": "eng", "value": "Multiple ZyXEL network-attached storage (NAS) devices running firmware version 5.21 contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable device. ZyXEL NAS devices achieve authentication by using the weblogin.cgi CGI executable. This program fails to properly sanitize the username parameter that is passed to it. If the username parameter contains certain characters, it can allow command injection with the privileges of the web server that runs on the ZyXEL device. Although the web server does not run as the root user, ZyXEL devices include a setuid utility that can be leveraged to run any command with root privileges. As such, it should be assumed that exploitation of this vulnerability can lead to remote code execution with root privileges. By sending a specially-crafted HTTP POST or GET request to a vulnerable ZyXEL device, a remote, unauthenticated attacker may be able to execute arbitrary code on the device. This may happen by directly connecting to a device if it is directly exposed to an attacker. However, there are ways to trigger such crafted requests even if an attacker does not have direct connectivity to a vulnerable devices. For example, simply visiting a website can result in the compromise of any ZyXEL device that is reachable from the client system. Affected products include: NAS326 before firmware V5.21(AAZF.7)C0 NAS520 before firmware V5.21(AASZ.3)C0 NAS540 before firmware V5.21(AATB.4)C0 NAS542 before firmware V5.21(ABAG.4)C0 ZyXEL has made firmware updates available for NAS326, NAS520, NAS540, and NAS542 devices. Affected models that are end-of-support: NSA210, NSA220, NSA220+, NSA221, NSA310, NSA310S, NSA320, NSA320S, NSA325 and NSA325v2"}]}, "problemtype": {"problemtype_data": [{"description": [{"lang": "eng", "value": "CWE-78 OS Command Injection"}]}]}, "work_around": [{"lang": "en", "value": "Block access to the ZyXEL device web interface:\n\nThis issue can be mitigated by blocking (for example with a firewall) access to the web interface (80/tcp and 443/tcp) of any vulnerable ZyXEL device. Any machine that can access the ZyXEL web interface should not also be able to access the internet.\n\nRestrict access to vulnerable ZyXEL devices:\n\nDirect exploitation of this vulnerability can be mitigated by restricting access to vulnerable devices. In particular, do not expose such devices directly to the internet. Note however, that it is still possible for attackers to exploit devices that are not directly connected to the internet. For example, by way of viewing a web page."}], "data_version": "4.0", "CVE_data_meta": {"ID": "CVE-2020-9054", "STATE": "PUBLIC", "TITLE": "ZyXEL NAS products running firmware version 5.21 and earlier are vulnerable to pre-authentication command injection in weblogin.cgi", "ASSIGNER": "cert@cert.org", "DATE_PUBLIC": "2020-02-20T00:00:00.000Z"}}}}, "cveMetadata": {"cveId": "CVE-2020-9054", "state": "PUBLISHED", "dateUpdated": "2025-10-21T19:54:38.314Z", "dateReserved": "2020-02-18T00:00:00.000Z", "assignerOrgId": "37e5125f-f79b-445b-8fad-9564f167944b", "datePublished": "2020-03-04T19:30:18.400Z", "assignerShortName": "certcc"}, "dataVersion": "5.1"}

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ZyXEL NAS devices achieve authentication by using the weblogin.cgi CGI executable. This program fails to properly sanitize the username parameter that is passed to it. If the username parameter contains certain characters, it can allow command injection with the privileges of the web server that runs on the ZyXEL device. Although the web server does not run as the root user, ZyXEL devices include a setuid utility that can be leveraged to run any command with root privileges. As such, it should be assumed that exploitation of this vulnerability can lead to remote code execution with root privileges. By sending a specially-crafted HTTP POST or GET request to a vulnerable ZyXEL device, a remote, unauthenticated attacker may be able to execute arbitrary code on the device. This may happen by directly connecting to a device if it is directly exposed to an attacker. However, there are ways to trigger such crafted requests even if an attacker does not have direct connectivity to a vulnerable devices. For example, simply visiting a website can result in the compromise of any ZyXEL device that is reachable from the client system. Affected products include: NAS326 before firmware V5.21(AAZF.7)C0 NAS520 before firmware V5.21(AASZ.3)C0 NAS540 before firmware V5.21(AATB.4)C0 NAS542 before firmware V5.21(ABAG.4)C0 ZyXEL has made firmware updates available for NAS326, NAS520, NAS540, and NAS542 devices. Affected models that are end-of-support: NSA210, NSA220, NSA220+, NSA221, NSA310, NSA310S, NSA320, NSA320S, NSA325 and NSA325v2"}, {"lang": "es", "value": "M\u00faltiples dispositivos network-attached storage (NAS) de ZyXEL cuando ejecutan la versi\u00f3n de firmware 5.21 contienen una vulnerabilidad de inyecci\u00f3n de comando previa a la autenticaci\u00f3n, que puede permitir a un atacante remoto no autenticado ejecutar c\u00f3digo arbitrario sobre un dispositivo vulnerable. Los dispositivos NAS de ZyXEL alcanzan la autenticaci\u00f3n utilizando el archivo ejecutable CGI weblogin.cgi. Este programa no puede sanear apropiadamente el par\u00e1metro username que se le pas\u00f3. Si el par\u00e1metro de username contiene determinados caracteres, puede permitir una inyecci\u00f3n de comandos con los privilegios del servidor web que se ejecuta en el dispositivo ZyXEL. Aunque el servidor web no es ejecutado como el usuario root, los dispositivos ZyXEL incluyen una utilidad setuid que puede ser aprovechada para ejecutar cualquier comando con privilegios root. Como tal, se debe suponer que la explotaci\u00f3n de esta vulnerabilidad puede conducir a la ejecuci\u00f3n remota de c\u00f3digo con privilegios root. Mediante el env\u00edo de una petici\u00f3n HTTP POST o GET especialmente dise\u00f1ada hacia un dispositivo ZyXEL vulnerable, un atacante remoto no autenticado puede ejecutar c\u00f3digo arbitrario en el dispositivo. Esto puede presentarse al conectar directamente a un dispositivo si es expuesto directamente a un atacante. Sin embargo, existen maneras de activar tales peticiones dise\u00f1adas inclusive si un atacante no posee conectividad directa con dispositivos vulnerables. Por ejemplo, simplemente visitando un sitio web puede comprometer cualquier dispositivo ZyXEL al que se pueda acceder desde el sistema cliente. Los productos afectados incluyen: NAS326 antes de la versi\u00f3n de firmware V5.21(AAZF.7)C0, NAS520 antes de la versi\u00f3n de firmware V5.21(AASZ.3)C0, NAS540 antes de la versi\u00f3n de firmware V5.21(AATB.4)C0 NAS542 antes de la versi\u00f3n de firmware V5.21(ABAG.4)C0. ZyXEL ha puesto a disposici\u00f3n actualizaciones de firmware para dispositivos NAS326, NAS520, NAS540 y NAS542. Modelos afectados que se encuentran en el final del soporte: NSA210, NSA220, NSA220+, NSA221, NSA310, NSA310S, NSA320, NSA320S, NSA325 y NSA325v2."}], "id": "CVE-2020-9054", "lastModified": "2025-10-21T20:18:10.290", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "HIGH", "cvssData": {"accessComplexity": "LOW", "accessVector": "NETWORK", "authentication": "NONE", "availabilityImpact": "COMPLETE", "baseScore": 10.0, "confidentialityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "vectorString": "AV:N/AC:L/Au:N/C:C/I:C/A:C", "version": "2.0"}, "exploitabilityScore": 10.0, "impactScore": 10.0, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "nvd@nist.gov", "type": "Primary", "userInteractionRequired": false}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "nvd@nist.gov", "type": "Primary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2020-03-04T20:15:10.750", "references": [{"source": "cret@cert.org", "tags": ["Third Party Advisory"], "url": "https://cwe.mitre.org/data/definitions/78.html"}, {"source": "cret@cert.org", "tags": ["Third Party Advisory", "US Government Resource"], "url": "https://kb.cert.org/artifacts/cve-2020-9054.html"}, {"source": "cret@cert.org", "tags": ["Third Party Advisory", "US Government Resource"], "url": "https://kb.cert.org/vuls/id/498544/"}, {"source": "cret@cert.org", "tags": ["Exploit", "Third Party Advisory"], "url": "https://krebsonsecurity.com/2020/02/zyxel-fixes-0day-in-network-storage-devices/"}, {"source": "cret@cert.org", "tags": ["Vendor Advisory"], "url": "https://www.zyxel.com/support/remote-code-execution-vulnerability-of-NAS-products.shtml"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory"], "url": "https://cwe.mitre.org/data/definitions/78.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory", "US Government Resource"], "url": "https://kb.cert.org/artifacts/cve-2020-9054.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory", "US Government Resource"], "url": "https://kb.cert.org/vuls/id/498544/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Third Party Advisory"], "url": "https://krebsonsecurity.com/2020/02/zyxel-fixes-0day-in-network-storage-devices/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Vendor Advisory"], "url": "https://www.zyxel.com/support/remote-code-execution-vulnerability-of-NAS-products.shtml"}], "sourceIdentifier": "cret@cert.org", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-78"}], "source": "cret@cert.org", "type": "Secondary"}, {"description": [{"lang": "en", "value": "CWE-78"}], "source": "nvd@nist.gov", "type": "Primary"}, {"description": [{"lang": "en", "value": "CWE-78"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

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