CVE-2026-39402

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The vulnerable check sits after the goto next label handling, meaning it is reachable on lines where earlier ownership checks failed or were skipped. Because nothing downstream of this authorization signal re-verifies that the matched database line actually belongs to the caller, an unprivileged attacker with a valid lxc-usernet policy entry can trigger deletion of another user's OVS port on the same bridge. \n\nThis is limited to multi-tenant environments using lxc-user-nic with OpenVSwitch bridges. The impact is denial of service - one tenant can repeatedly disconnect networking from containers run by another tenant on shared infrastructure. This is patched in version 7.0.0."}, {"lang": "es", "value": "lxc es un tiempo de ejecuci\u00f3n de contenedores Linux. En el asistente setuid lxc-user-nic, la ruta de eliminaci\u00f3n contiene un fallo l\u00f3gico en la funci\u00f3n find_line() que permite a un usuario sin privilegios eliminar interfaces de red conectadas a OVS que pertenecen a otros usuarios. Cuando lxc-user-nic delete escanea su base de datos NIC para autorizar una solicitud de eliminaci\u00f3n, la comparaci\u00f3n del nombre de la interfaz puede establecer el indicador de autorizaci\u00f3n bas\u00e1ndose \u00fanicamente en una coincidencia de nombre, incluso cuando los campos de propiedad, tipo y enlace en esa entrada de base de datos pertenecen a un usuario diferente. La comprobaci\u00f3n vulnerable se encuentra despu\u00e9s del manejo de la etiqueta goto next, lo que significa que es accesible en l\u00edneas donde las comprobaciones de propiedad anteriores fallaron o fueron omitidas. Debido a que nada posterior a esta se\u00f1al de autorizaci\u00f3n vuelve a verificar que la l\u00ednea de la base de datos coincidente realmente pertenece al llamador, un atacante sin privilegios con una entrada de pol\u00edtica lxc-usernet v\u00e1lida puede desencadenar la eliminaci\u00f3n del puerto OVS de otro usuario en el mismo puente.\n\nEsto se limita a entornos multi-inquilino que utilizan lxc-user-nic con puentes OpenVSwitch. El impacto es denegaci\u00f3n de servicio: un inquilino puede desconectar repetidamente la red de los contenedores ejecutados por otro inquilino en infraestructura compartida. Esto est\u00e1 parcheado en la versi\u00f3n 7.0.0."}], "id": "CVE-2026-39402", "lastModified": "2026-07-24T21:10:00.143", "metrics": {"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"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "LOCAL", "availabilityRequirement": "NOT_DEFINED", "baseScore": 4.3, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "LOW", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-39402", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-05-06T14:57:00.498118Z", "version": "2.0.3"}}]}, "published": "2026-05-05T21:16:22.537", "references": [{"source": "security-advisories@github.com", "tags": ["Exploit", "Vendor Advisory"], "url": "https://github.com/lxc/lxc/security/advisories/GHSA-3m9j-g9gc-vcvq"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"], "url": "https://github.com/lxc/lxc/security/advisories/GHSA-3m9j-g9gc-vcvq"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-863"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

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