CVE-2020-25601

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{"affected": [{"affectedData": [{"product": "n/a", "vendor": "n/a", "versions": [{"status": "affected", "version": "n/a"}]}], "source": "cve@mitre.org"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*", "matchCriteriaId": "2D769F4A-98C6-4544-AC04-3D8600C17BBB", "versionEndIncluding": "4.14.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*", "matchCriteriaId": "07B237A9-69A3-4A9C-9DA0-4E06BD37AE73", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*", "matchCriteriaId": "80F0FA5D-8D3B-4C0E-81E2-87998286AF33", "vulnerable": true}, {"criteria": "cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*", "matchCriteriaId": "36D96259-24BD-44E2-96D9-78CE1D41F956", "vulnerable": true}, {"criteria": "cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*", "matchCriteriaId": "E460AA51-FCDA-46B9-AE97-E6676AA5E194", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*", "matchCriteriaId": "B009C22E-30A4-4288-BCF6-C3E81DEAF45A", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions are vulnerable in principle. Whether versions 4.3 and older are vulnerable depends on underlying hardware characteristics."}, {"lang": "es", "value": "Se detect\u00f3 un problema en Xen versiones hasta 4.14.x. Se presenta una carencia de preferencia en evtchn_reset() / evtchn_destroy(). En particular, el modelo de canal de eventos FIFO permite a los invitados tener una gran cantidad de canales de eventos activos simult\u00e1neos. Cerrar todos estos (al restablecer todos los canales de eventos o al limpiar despu\u00e9s del invitado) puede llevar per\u00edodos de tiempo prolongados. Hasta ahora, no hab\u00eda ning\u00fan arreglo para la preferencia a intervalos adecuados, lo que permit\u00eda que una CPU pasara una cantidad de tiempo casi ilimitada en el procesamiento de estas operaciones. Los kernels invitados maliciosos o con errores pueden montar un ataque de denegaci\u00f3n de servicio (DoS) afectando a todo el sistema. Todas las versiones de Xen son vulnerables en principio. Tanto las versiones 4.3 y como las anteriores son vulnerables dependiendo de las caracter\u00edsticas subyacentes del hardware."}], "id": "CVE-2020-25601", "lastModified": "2026-06-17T03:06:57.593", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "MEDIUM", "cvssData": {"accessComplexity": "LOW", "accessVector": "LOCAL", "authentication": "NONE", "availabilityImpact": "COMPLETE", "baseScore": 4.9, "confidentialityImpact": "NONE", "integrityImpact": "NONE", "vectorString": "AV:L/AC:L/Au:N/C:N/I:N/A:C", "version": "2.0"}, "exploitabilityScore": 3.9, "impactScore": 6.9, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "nvd@nist.gov", "type": "Primary", "userInteractionRequired": false}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2020-09-23T22:15:13.713", "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": ["Vendor Advisory"], "url": "https://xenbits.xen.org/xsa/advisory-344.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": ["Vendor Advisory"], "url": "https://xenbits.xen.org/xsa/advisory-344.html"}], "sourceIdentifier": "cve@mitre.org", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"acknowledgement": "Red Hat would like to thank the Xen project for reporting this issue.", "bugzilla": {"description": "xen: lack of preemption in evtchn_reset() / evtchn_destroy() (XSA-344)", "id": "1877378", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1877378"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-400", "details": ["An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions are vulnerable in principle. Whether versions 4.3 and older are vulnerable depends on underlying hardware characteristics.", "A security flaw was found in Xen. A lack of preemption in the FIFO event channel model may cause the CPU to spend an almost unbounded amount of processing time. This flaw allows malicious or buggy guest kernels to mount a denial of service (DoS) attack affecting the entire system. The highest threat from this vulnerability is to system availability."], "mitigation": {"lang": "en:us", "value": "This issue can be avoided by reducing the number of event channels available to all guests to a suitably low limit. For example, setting \"max_event_channels=256\" in the xl domain configurations may be low enough for all hardware Xen is able to run on."}, "name": "CVE-2020-25601", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:5", "fix_state": "Out of support scope", "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-2020-25601\nhttps://nvd.nist.gov/vuln/detail/CVE-2020-25601\nhttps://xenbits.xen.org/xsa/advisory-344.html"], "statement": "This flaw has been rated as having a security impact of Moderate, and is not currently planned to be addressed in future updates of Red Hat Enterprise Linux 5. Red Hat Enterprise Linux 5 is now in Extended Life Phase of the support and maintenance life cycle. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.", "threat_severity": "Moderate"}

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