CVE-2026-43363

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This causes the kernel to continue using the\nxapic interface, while the hardware is in x2apic mode, which causes hangs.\nThis happens on defconfig + bare metal + s2ram.\n\nFix this in lapic_resume() by disabling x2apic if the kernel expects it to be\ndisabled, i.e. when x2apic_mode = 0.\n\nThe ACPI v6.6 spec, Section 16.3 [1] says firmware restores either the\npre-sleep configuration or initial boot configuration for each CPU, including\nMSR state:\n\n When executing from the power-on reset vector as a result of waking from an\n S2 or S3 sleep state, the platform firmware performs only the hardware\n initialization required to restore the system to either the state the\n platform was in prior to the initial operating system boot, or to the\n pre-sleep configuration state. In multiprocessor systems, non-boot\n processors should be placed in the same state as prior to the initial\n operating system boot.\n\n (further ahead)\n\n If this is an S2 or S3 wake, then the platform runtime firmware restores\n minimum context of the system before jumping to the waking vector. This\n includes:\n\n\tCPU configuration. Platform runtime firmware restores the pre-sleep\n\tconfiguration or initial boot configuration of each CPU (MSR, MTRR,\n\tfirmware update, SMBase, and so on). Interrupts must be disabled (for\n\tIA-32 processors, disabled by CLI instruction).\n\n\t(and other things)\n\nSo at least as per the spec, re-enablement of x2apic by the firmware is\nallowed if \"x2apic on\" is a part of the initial boot configuration.\n\n [1] https://uefi.org/specs/ACPI/6.6/16_Waking_and_Sleeping.html#initialization\n\n [ bp: Massage. ]"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/x86/kernel/apic/apic.c"], "versions": [{"version": "6e1cb38a2aef7680975e71f23de187859ee8b158", "lessThan": "a6ad6f2e31b524cbb66b2f370bad0cf17d327e6c", "status": "affected", "versionType": "git"}, {"version": "6e1cb38a2aef7680975e71f23de187859ee8b158", "lessThan": "3dd0812a7c764cd8f3b0182441ac22da0a7f3b09", "status": "affected", "versionType": "git"}, {"version": "6e1cb38a2aef7680975e71f23de187859ee8b158", "lessThan": 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This causes the kernel to continue using the\nxapic interface, while the hardware is in x2apic mode, which causes hangs.\nThis happens on defconfig + bare metal + s2ram.\n\nFix this in lapic_resume() by disabling x2apic if the kernel expects it to be\ndisabled, i.e. when x2apic_mode = 0.\n\nThe ACPI v6.6 spec, Section 16.3 [1] says firmware restores either the\npre-sleep configuration or initial boot configuration for each CPU, including\nMSR state:\n\n When executing from the power-on reset vector as a result of waking from an\n S2 or S3 sleep state, the platform firmware performs only the hardware\n initialization required to restore the system to either the state the\n platform was in prior to the initial operating system boot, or to the\n pre-sleep configuration state. 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"versionEndExcluding": "6.18.19", "versionStartIncluding": "6.13", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "E825E7C3-FEAC-4FD3-8A81-78D7387948C9", "versionEndExcluding": "6.19.9", "versionStartIncluding": "6.19", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/apic: Disable x2apic on resume if the kernel expects so\n\nWhen resuming from s2ram, firmware may re-enable x2apic mode, which may have\nbeen disabled by the kernel during boot either because it doesn't support IRQ\nremapping or for other reasons. This causes the kernel to continue using the\nxapic interface, while the hardware is in x2apic mode, which causes hangs.\nThis happens on defconfig + bare metal + s2ram.\n\nFix this in lapic_resume() by disabling x2apic if the kernel expects it to be\ndisabled, i.e. when x2apic_mode = 0.\n\nThe ACPI v6.6 spec, Section 16.3 [1] says firmware restores either the\npre-sleep configuration or initial boot configuration for each CPU, including\nMSR state:\n\n When executing from the power-on reset vector as a result of waking from an\n S2 or S3 sleep state, the platform firmware performs only the hardware\n initialization required to restore the system to either the state the\n platform was in prior to the initial operating system boot, or to the\n pre-sleep configuration state. In multiprocessor systems, non-boot\n processors should be placed in the same state as prior to the initial\n operating system boot.\n\n (further ahead)\n\n If this is an S2 or S3 wake, then the platform runtime firmware restores\n minimum context of the system before jumping to the waking vector. This\n includes:\n\n\tCPU configuration. Platform runtime firmware restores the pre-sleep\n\tconfiguration or initial boot configuration of each CPU (MSR, MTRR,\n\tfirmware update, SMBase, and so on). Interrupts must be disabled (for\n\tIA-32 processors, disabled by CLI instruction).\n\n\t(and other things)\n\nSo at least as per the spec, re-enablement of x2apic by the firmware is\nallowed if \"x2apic on\" is a part of the initial boot configuration.\n\n [1] https://uefi.org/specs/ACPI/6.6/16_Waking_and_Sleeping.html#initialization\n\n [ bp: Massage. ]"}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nx86/apic: Deshabilitar x2apic al reanudar si el kernel as\u00ed lo espera\n\nAl reanudar desde s2ram, el firmware puede volver a habilitar el modo x2apic, el cual pudo haber sido deshabilitado por el kernel durante el arranque, ya sea porque no soporta la reasignaci\u00f3n de IRQ o por otras razones. Esto hace que el kernel contin\u00fae usando la interfaz xapic, mientras el hardware est\u00e1 en modo x2apic, lo que causa bloqueos. Esto ocurre en defconfig + bare metal + s2ram.\n\nEsto se soluciona en lapic_resume() deshabilitando x2apic si el kernel espera que est\u00e9 deshabilitado, es decir, cuando x2apic_mode = 0.\n\nLa especificaci\u00f3n ACPI v6.6, Secci\u00f3n 16.3 [1] dice que el firmware restaura la configuraci\u00f3n previa al reposo o la configuraci\u00f3n de arranque inicial para cada CPU, incluyendo el estado MSR:\n\n Al ejecutar desde el vector de reinicio de encendido como resultado de despertar de un estado de reposo S2 o S3, el firmware de la plataforma realiza solo la inicializaci\u00f3n de hardware requerida para restaurar el sistema al estado en que se encontraba la plataforma antes del arranque inicial del sistema operativo, o al estado de configuraci\u00f3n previa al reposo. En sistemas multiprocesador, los procesadores que no son de arranque deben colocarse en el mismo estado que antes del arranque inicial del sistema operativo.\n\n (m\u00e1s adelante)\n\n Si se trata de un despertar S2 o S3, entonces el firmware de tiempo de ejecuci\u00f3n de la plataforma restaura el contexto m\u00ednimo del sistema antes de saltar al vector de despertar. Esto incluye:\n\n\tConfiguraci\u00f3n de la CPU. El firmware de tiempo de ejecuci\u00f3n de la plataforma restaura la configuraci\u00f3n previa al reposo o la configuraci\u00f3n de arranque inicial de cada CPU (MSR, MTRR, actualizaci\u00f3n de firmware, SMBase, y as\u00ed sucesivamente). Las interrupciones deben estar deshabilitadas (para procesadores IA-32, deshabilitadas por la instrucci\u00f3n CLI).\n\n\t(y otras cosas)\n\nAs\u00ed que, al menos seg\u00fan la especificaci\u00f3n, la reactivaci\u00f3n de x2apic por parte del firmware est\u00e1 permitida si \u2019x2apic on\u2019 es parte de la configuraci\u00f3n de arranque inicial.\n\n [1] https://uefi.org/specs/ACPI/6.6/16_Waking_and_Sleeping.html#initialization\n\n [ bp: Massage. ]"}], "id": "CVE-2026-43363", "lastModified": "2026-11-11T20:10:00.273", "metrics": {"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"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-43363", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-11-06T15:36:29.822494Z", "version": "2.0.3"}}]}, "published": "2026-05-08T15:16:47.247", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/11712c4eb384098db4cb08792e223c818b908c1a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/1a85f84214f9d790216547ac6086bf8033cd9e5a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/1d8440c1e7c49715f937416ac90cf260f1f1712c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/3dd0812a7c764cd8f3b0182441ac22da0a7f3b09"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/8cc7dd77a1466f0ec58c03478b2e735a5b289b96"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/965289b120cc68cca886c75219c68b8c15751d73"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a6ad6f2e31b524cbb66b2f370bad0cf17d327e6c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/f591938072115bf08730b8530c67fab189cc6308"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: x86/apic: Disable x2apic on resume if the kernel expects so", "id": "2468213", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2468213"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-372", "details": ["A flaw was found in the Linux kernel. When resuming from suspend to RAM (s2ram), the system's firmware may incorrectly re-enable x2apic mode, even if the kernel had previously disabled it. This mismatch causes the kernel to operate with an incompatible interface, leading to system hangs and a Denial of Service."], "name": "CVE-2026-43363", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-05-08T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-43363\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-43363\nhttps://lore.kernel.org/linux-cve-announce/2026050827-CVE-2026-43363-9ff7@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6e1cb38a2aef7680975e71f23de187859ee8b158,a6ad6f2e31b524cbb66b2f370bad0cf17d327e6c)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6e1cb38a2aef7680975e71f23de187859ee8b158,3dd0812a7c764cd8f3b0182441ac22da0a7f3b09)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6e1cb38a2aef7680975e71f23de187859ee8b158,965289b120cc68cca886c75219c68b8c15751d73)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6e1cb38a2aef7680975e71f23de187859ee8b158,f591938072115bf08730b8530c67fab189cc6308)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6e1cb38a2aef7680975e71f23de187859ee8b158,1a85f84214f9d790216547ac6086bf8033cd9e5a)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6e1cb38a2aef7680975e71f23de187859ee8b158,11712c4eb384098db4cb08792e223c818b908c1a)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6e1cb38a2aef7680975e71f23de187859ee8b158,1d8440c1e7c49715f937416ac90cf260f1f1712c)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[6e1cb38a2aef7680975e71f23de187859ee8b158,8cc7dd77a1466f0ec58c03478b2e735a5b289b96)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "2.6.28"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,2.6.28)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.10.253,6.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.15.203,6.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.1.167,7.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.130,7.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.78,7.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.19,7.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.19.9,7.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.0,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-05-08T16:15:12.713311+00:00", "updated": "2026-05-15T18:15:05.633323+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}