CVE-2019-19578

{"id": "CVE-2019-19578", "metrics": {"cvssMetricV2": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"version": "2.0", "baseScore": 7.2, "accessVector": "LOCAL", "vectorString": "AV:L/AC:L/Au:N/C:C/I:C/A:C", "authentication": "NONE", "integrityImpact": "COMPLETE", "accessComplexity": "LOW", "availabilityImpact": "COMPLETE", "confidentialityImpact": "COMPLETE"}, "acInsufInfo": false, "impactScore": 10.0, "baseSeverity": "HIGH", "obtainAllPrivilege": false, "exploitabilityScore": 3.9, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "CHANGED", "version": "3.1", "baseScore": 8.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}, "impactScore": 6.0, "exploitabilityScore": 2.0}]}, "published": "2019-12-11T18:16:19.333", "references": [{"url": "http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html", "source": "cve@mitre.org"}, {"url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/", "source": "cve@mitre.org"}, {"url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/", "source": "cve@mitre.org"}, {"url": "https://seclists.org/bugtraq/2020/Jan/21", "source": "cve@mitre.org"}, {"url": "https://security.gentoo.org/glsa/202003-56", "source": "cve@mitre.org"}, {"url": "https://www.debian.org/security/2020/dsa-4602", "source": "cve@mitre.org"}, {"url": "https://xenbits.xen.org/xsa/advisory-309.html", "tags": ["Patch", "Vendor Advisory"], "source": "cve@mitre.org"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-682"}]}], "descriptions": [{"lang": "en", "value": "An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to cause a denial of service via degenerate chains of linear pagetables, because of an incorrect fix for CVE-2017-15595. \"Linear pagetables\" is a technique which involves either pointing a pagetable at itself, or to another pagetable of the same or higher level. Xen has limited support for linear pagetables: A page may either point to itself, or point to another pagetable of the same level (i.e., L2 to L2, L3 to L3, and so on). XSA-240 introduced an additional restriction that limited the \"depth\" of such chains by allowing pages to either *point to* other pages of the same level, or *be pointed to* by other pages of the same level, but not both. To implement this, we keep track of the number of outstanding times a page points to or is pointed to another page table, to prevent both from happening at the same time. Unfortunately, the original commit introducing this reset this count when resuming validation of a partially-validated pagetable, incorrectly dropping some \"linear_pt_entry\" counts. If an attacker could engineer such a situation to occur, they might be able to make loops or other arbitrary chains of linear pagetables, as described in XSA-240. A malicious or buggy PV guest may cause the hypervisor to crash, resulting in Denial of Service (DoS) affecting the entire host. Privilege escalation and information leaks cannot be excluded. All versions of Xen are vulnerable. Only x86 systems are affected. Arm systems are not affected. Only x86 PV guests can leverage the vulnerability. x86 HVM and PVH guests cannot leverage the vulnerability. Only systems which have enabled linear pagetables are vulnerable. Systems which have disabled linear pagetables, either by selecting CONFIG_PV_LINEAR_PT=n when building the hypervisor, or adding pv-linear-pt=false on the command-line, are not vulnerable."}, {"lang": "es", "value": "Se detect\u00f3 un problema en Xen versiones hasta 4.12.x permitiendo a usuarios del Sistema Operativo invitado PV en x86 causar una denegaci\u00f3n de servicio por medio de cadenas degeneradas de tablas de p\u00e1ginas lineales, debido a una correcci\u00f3n incorrecta para CVE-2017-15595. \"Linear pagetables\" es una t\u00e9cnica que consiste en se\u00f1alar una tabla de p\u00e1ginas en s\u00ed misma o en otra tabla de p\u00e1ginas del mismo nivel o superior. Xen tiene soporte limitado para tablas de p\u00e1ginas lineales: una p\u00e1gina puede apuntar hacia s\u00ed misma o hacia otra tabla de p\u00e1ginas del mismo nivel (es decir, L2 a L2, L3 a L3, etc.). XSA-240 introdujo una restricci\u00f3n adicional que limit\u00f3 la \"depth\" de tales cadenas al permitir que las p\u00e1ginas * apunten * a otras p\u00e1ginas del mismo nivel, o * sean se\u00f1aladas * por otras p\u00e1ginas del mismo nivel, pero no ambas. Para implementar esto, hacemos un seguimiento del n\u00famero de veces pendientes que una p\u00e1gina se\u00f1ala o apunta a otra tabla de p\u00e1ginas, para evitar que ambas sucedan al mismo tiempo. Desafortunadamente, la confirmaci\u00f3n original que introduce este restablecimiento de este recuento al reanudar la comprobaci\u00f3n de una tabla de p\u00e1ginas parcialmente validada, eliminando incorrectamente algunos recuentos de \"linear_pt_entry\". Si un atacante pudiera dise\u00f1ar una situaci\u00f3n as\u00ed, podr\u00eda hacer bucles u otras cadenas arbitrarias de tablas lineales, como se describe en XSA-240. Un invitado PV malicioso o con errores puede hacer que el hipervisor se bloquee, resultando en la denegaci\u00f3n de servicio (DoS) que afecta a todo el host. La escalada de privilegios y las filtraciones de informaci\u00f3n no se pueden excluir. Todas las versiones de Xen son vulnerables. Solo los sistemas en x86 est\u00e1n afectados. Los sistemas ARM no est\u00e1n afectados. Solo los invitados de PV en x86 pueden aprovechar la vulnerabilidad. Los invitados x86 HVM y PVH no pueden aprovechar la vulnerabilidad. Solo los sistemas que han habilitado tablas de p\u00e1ginas lineales son vulnerables. Los sistemas que han deshabilitado las tablas de p\u00e1ginas lineales, ya sea seleccionando CONFIG_PV_LINEAR_PT = n al construir el hipervisor, o agregando pv-linear-pt = false en la l\u00ednea de comandos, no son vulnerables."}], "lastModified": "2023-11-07T03:07:42.143", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:*", "vulnerable": true, "matchCriteriaId": "18F9F58D-58A0-4356-AB70-E5ACF913BFCA", "versionEndIncluding": "4.12.1"}], "operator": "OR"}]}, {"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "80F0FA5D-8D3B-4C0E-81E2-87998286AF33"}], "operator": "OR"}]}], "sourceIdentifier": "cve@mitre.org"}