{"containers": {"cna": {"affected": [{"product": "n/a", "vendor": "n/a", "versions": [{"status": "affected", "version": "n/a"}]}], "descriptions": [{"lang": "en", "value": "An issue was discovered in Xen through 4.14.x. There is mishandling of the constraint that once-valid event channels may not turn invalid. Logic in the handling of event channel operations in Xen assumes that an event channel, once valid, will not become invalid over the life time of a guest. However, operations like the resetting of all event channels may involve decreasing one of the bounds checked when determining validity. This may lead to bug checks triggering, crashing the host. An unprivileged guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. All Xen versions from 4.4 onwards are vulnerable. Xen versions 4.3 and earlier are not vulnerable. Only systems with untrusted guests permitted to create more than the default number of event channels are vulnerable. This number depends on the architecture and type of guest. For 32-bit x86 PV guests, this is 1023; for 64-bit x86 PV guests, and for all ARM guests, this number is 4095. Systems where untrusted guests are limited to fewer than this number are not vulnerable. Note that xl and libxl limit max_event_channels to 1023 by default, so systems using exclusively xl, libvirt+libxl, or their own toolstack based on libxl, and not explicitly setting max_event_channels, are not vulnerable."}], "problemTypes": [{"descriptions": [{"description": "n/a", "lang": "en", "type": "text"}]}], "providerMetadata": {"dateUpdated": "2020-11-11T05:06:36", "orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca", "shortName": "mitre"}, "references": [{"tags": ["x_refsource_MISC"], "url": "https://xenbits.xen.org/xsa/advisory-338.html"}, {"name": "FEDORA-2020-306b84fd07", "tags": ["vendor-advisory", "x_refsource_FEDORA"], "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4JRXMKEMQRQYWYEPHVBIWUEAVQ3LU4FN/"}, {"name": "FEDORA-2020-f668e579be", "tags": ["vendor-advisory", "x_refsource_FEDORA"], "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DA633Y3G5KX7MKRN4PFEGM3IVTJMBEOM/"}, {"name": "DSA-4769", "tags": ["vendor-advisory", "x_refsource_DEBIAN"], "url": "https://www.debian.org/security/2020/dsa-4769"}, {"name": "openSUSE-SU-2020:1608", "tags": ["vendor-advisory", "x_refsource_SUSE"], "url": "http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00008.html"}, {"name": "FEDORA-2020-d46fe34349", "tags": ["vendor-advisory", "x_refsource_FEDORA"], "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RJZERRBJN6E6STDCHT4JHP4MI6TKBCJE/"}, {"name": "GLSA-202011-06", "tags": ["vendor-advisory", "x_refsource_GENTOO"], "url": "https://security.gentoo.org/glsa/202011-06"}], "x_legacyV4Record": {"CVE_data_meta": {"ASSIGNER": "cve@mitre.org", "ID": "CVE-2020-25597", "STATE": "PUBLIC"}, "affects": {"vendor": {"vendor_data": [{"product": {"product_data": [{"product_name": "n/a", "version": {"version_data": [{"version_value": "n/a"}]}}]}, "vendor_name": "n/a"}]}}, "data_format": "MITRE", "data_type": "CVE", "data_version": "4.0", "description": {"description_data": [{"lang": "eng", "value": "An issue was discovered in Xen through 4.14.x. There is mishandling of the constraint that once-valid event channels may not turn invalid. Logic in the handling of event channel operations in Xen assumes that an event channel, once valid, will not become invalid over the life time of a guest. However, operations like the resetting of all event channels may involve decreasing one of the bounds checked when determining validity. This may lead to bug checks triggering, crashing the host. An unprivileged guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. All Xen versions from 4.4 onwards are vulnerable. Xen versions 4.3 and earlier are not vulnerable. Only systems with untrusted guests permitted to create more than the default number of event channels are vulnerable. This number depends on the architecture and type of guest. For 32-bit x86 PV guests, this is 1023; for 64-bit x86 PV guests, and for all ARM guests, this number is 4095. Systems where untrusted guests are limited to fewer than this number are not vulnerable. 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{}

{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*", "matchCriteriaId": "4DA128DD-C679-4900-81EA-E74C02198307", "versionEndIncluding": "4.14.0", "versionStartIncluding": "4.4.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*", "matchCriteriaId": "80F0FA5D-8D3B-4C0E-81E2-87998286AF33", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "descriptions": [{"lang": "en", "value": "An issue was discovered in Xen through 4.14.x. There is mishandling of the constraint that once-valid event channels may not turn invalid. Logic in the handling of event channel operations in Xen assumes that an event channel, once valid, will not become invalid over the life time of a guest. However, operations like the resetting of all event channels may involve decreasing one of the bounds checked when determining validity. This may lead to bug checks triggering, crashing the host. An unprivileged guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. All Xen versions from 4.4 onwards are vulnerable. Xen versions 4.3 and earlier are not vulnerable. Only systems with untrusted guests permitted to create more than the default number of event channels are vulnerable. This number depends on the architecture and type of guest. For 32-bit x86 PV guests, this is 1023; for 64-bit x86 PV guests, and for all ARM guests, this number is 4095. Systems where untrusted guests are limited to fewer than this number are not vulnerable. Note that xl and libxl limit max_event_channels to 1023 by default, so systems using exclusively xl, libvirt+libxl, or their own toolstack based on libxl, and not explicitly setting max_event_channels, are not vulnerable."}, {"lang": "es", "value": "Se detect\u00f3 un problema en Xen versiones hasta 4.14.x. Existe un manejo inapropiado de la restricci\u00f3n de que los canales de eventos que una vez fueron v\u00e1lidos no pueden volverse no v\u00e1lidos. La l\u00f3gica en el manejo de las operaciones del canal de eventos en Xen asume que un canal de eventos, una vez v\u00e1lido, no dejar\u00e1 de serlo durante la vida \u00fatil de un invitado. Sin embargo, operaciones como el restablecimiento de todos los canales de eventos pueden implicar la disminuci\u00f3n de uno de los l\u00edmites comprobados al determinar la validez. Esto puede provocar que se activen las comprobaciones de errores y que el host se bloquee. Un invitado sin privilegios puede bloquear Xen, conllevando a una Denegaci\u00f3n de servicio (DoS) para todo el sistema. Todas las versiones de Xen desde 4.4 en adelante son vulnerables. Las versiones 4.3 y anteriores de Xen no son vulnerables. Solo los sistemas con invitados que no son de confianza y que tienen permitido crear m\u00e1s canales de eventos que el n\u00famero predeterminado son vulnerables. Este n\u00famero depende de la arquitectura y el tipo de invitado. Para invitados PV x86 de 32 bits, es 1023; para invitados PV x86 de 64 bits y para todos los invitados ARM, este n\u00famero es 4095. Los sistemas en los que los invitados que no son de confianza est\u00e1n limitados a menos de este n\u00famero no son vulnerables. Tome en cuenta que xl y libxl limitan max_event_channels a 1023 de forma predeterminada, por lo que los sistemas que usan exclusivamente xl, libvirt + libxl o su propio conjunto de herramientas basado en libxl, y que no establecen expl\u00edcitamente max_event_channels, no son vulnerables"}], "id": "CVE-2020-25597", "lastModified": "2024-11-21T05:18:11.713", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "MEDIUM", "cvssData": {"accessComplexity": "LOW", "accessVector": "LOCAL", "authentication": "NONE", "availabilityImpact": "COMPLETE", "baseScore": 6.1, "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "vectorString": "AV:L/AC:L/Au:N/C:P/I:P/A:C", "version": "2.0"}, "exploitabilityScore": 3.9, "impactScore": 8.5, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "nvd@nist.gov", "type": "Primary", "userInteractionRequired": false}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.0, "impactScore": 4.0, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2020-09-23T22:15:13.307", "references": [{"source": "cve@mitre.org", "tags": ["Mailing List", "Third Party Advisory"], "url": "http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00008.html"}, {"source": "cve@mitre.org", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4JRXMKEMQRQYWYEPHVBIWUEAVQ3LU4FN/"}, {"source": "cve@mitre.org", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DA633Y3G5KX7MKRN4PFEGM3IVTJMBEOM/"}, {"source": "cve@mitre.org", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RJZERRBJN6E6STDCHT4JHP4MI6TKBCJE/"}, {"source": "cve@mitre.org", "tags": ["Third Party Advisory"], "url": "https://security.gentoo.org/glsa/202011-06"}, {"source": "cve@mitre.org", "tags": ["Third Party Advisory"], "url": "https://www.debian.org/security/2020/dsa-4769"}, {"source": "cve@mitre.org", "tags": ["Patch", "Vendor Advisory"], "url": "https://xenbits.xen.org/xsa/advisory-338.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Third Party Advisory"], "url": "http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00008.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4JRXMKEMQRQYWYEPHVBIWUEAVQ3LU4FN/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DA633Y3G5KX7MKRN4PFEGM3IVTJMBEOM/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RJZERRBJN6E6STDCHT4JHP4MI6TKBCJE/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory"], "url": "https://security.gentoo.org/glsa/202011-06"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory"], "url": "https://www.debian.org/security/2020/dsa-4769"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch", "Vendor Advisory"], "url": "https://xenbits.xen.org/xsa/advisory-338.html"}], "sourceIdentifier": "cve@mitre.org", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-755"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"acknowledgement": "Red Hat would like to thank the Xen project for reporting this issue.", "bugzilla": {"description": "xen: once valid event channels may not turn invalid (XSA-338)", "id": "1879553", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1879553"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-440", "details": ["An issue was discovered in Xen through 4.14.x. There is mishandling of the constraint that once-valid event channels may not turn invalid. Logic in the handling of event channel operations in Xen assumes that an event channel, once valid, will not become invalid over the life time of a guest. However, operations like the resetting of all event channels may involve decreasing one of the bounds checked when determining validity. This may lead to bug checks triggering, crashing the host. An unprivileged guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. All Xen versions from 4.4 onwards are vulnerable. Xen versions 4.3 and earlier are not vulnerable. Only systems with untrusted guests permitted to create more than the default number of event channels are vulnerable. This number depends on the architecture and type of guest. For 32-bit x86 PV guests, this is 1023; for 64-bit x86 PV guests, and for all ARM guests, this number is 4095. Systems where untrusted guests are limited to fewer than this number are not vulnerable. Note that xl and libxl limit max_event_channels to 1023 by default, so systems using exclusively xl, libvirt+libxl, or their own toolstack based on libxl, and not explicitly setting max_event_channels, are not vulnerable.", "A logic flaw was found in the handling of event channel operations in Xen. Operations such as resetting all event channels may involve decreasing one of the bounds checked when determining validity. This flaw allows an unprivileged guest to crash Xen, leading to a denial of service (DoS) for the entire system. The highest threat from this vulnerability is to system availability."], "mitigation": {"lang": "en:us", "value": "The issue can be avoided by reducing the number of event channels available to the guest to no more than 1023. For example, setting `max_event_channels=1023` in the xl domain configuration, or deleting any existing setting (since 1023 is the default for xl/libxl).\nFor ARM systems, any limit no more than 4095 is safe. For 64-bit x86 PV guests, any limit no more than 4095 is likewise safe if the host configuration prevents the guest administrator from substituting and running a 32-bit kernel (and thereby putting the guest into 32-bit PV mode)."}, "name": "CVE-2020-25597", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:5", "fix_state": "Not affected", "package_name": "kernel-xen", "product_name": "Red Hat Enterprise Linux 5"}], "public_date": "2020-09-22T12:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2020-25597\nhttps://nvd.nist.gov/vuln/detail/CVE-2020-25597\nhttps://xenbits.xen.org/xsa/advisory-338.html"], "statement": "All Xen versions from 4.4 onwards are vulnerable. Red Hat Enterprise Linux 5 is not affected by this flaw, as it shipped an older version of Xen.", "threat_severity": "Moderate"}