CVE-2026-74516

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74516", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.910Z", "datePublished": "2026-08-15T12:27:36.200Z", "dateUpdated": "2026-10-16T19:05:52.090Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-19T16:38:16.902Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active\n\nAlways update x2APIC MSR intercepts for L1 when AVIC is deactivated, even\nif L2 is active and KVM is using a separate MSR bitmap to run L2. If AVIC\nis fully enabled prior to running L2, and is then inhibited while L2 is\nactive (for a VM-scoped inhibit), then KVM will run L1 with AVIC disabled,\nbut with x2APIC MSR intercepts disabled, i.e. will allow L1 to read most of\nthe host's APIC state, send arbitrary interrupts, change task priority, and\nultimately trivially DoS the host.\n\nE.g. sending a self-IPI in L1 on HYPERV_REENLIGHTENMENT_VECTOR, 0xee, with\nCONFIG_HYPERV=n in the host kernel as a \"safe\" PoC, yields:\n\n Spurious interrupt (vector 0xee) on CPU#425. Acked\n\nAnd hacking KVM to abuse kvm_set_posted_intr_wakeup_handler() to register a\nhandler and WARN on POSTED_INTR_WAKEUP_VECTOR yields:\n\n ------------[ cut here ]------------\n WARNING: arch/x86/kvm/svm/svm.c:5594 at pi_wakeup_handler+0x9/0x10 [kvm_amd], CPU#156: nested_x2apic_t/316940\n CPU: 156 UID: 0 PID: 316940 Comm: nested_x2apic_t Tainted: G S U\n Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER\n Hardware name: Google Astoria-Turin/astoria, BIOS 0.20260209.0-0 02/09/2026\n RIP: 0010:pi_wakeup_handler+0x9/0x10 [kvm_amd]\n Call Trace:\n <IRQ>\n sysvec_kvm_posted_intr_wakeup_ipi+0x64/0x80\n </IRQ>\n <TASK>\n asm_sysvec_kvm_posted_intr_wakeup_ipi+0x1a/0x20\n RIP: 0010:vcpu_run+0x1430/0x1e40 [kvm]\n kvm_arch_vcpu_ioctl_run+0x2c1/0x600 [kvm]\n kvm_vcpu_ioctl+0x580/0x6b0 [kvm]\n __se_sys_ioctl+0x6d/0xb0\n do_syscall_64+0x10a/0x480\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x46ff4b\n </TASK>\n ---[ end trace 0000000000000000 ]---"}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.2, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - Exploitation requires triggering KVM nested SVM/AVIC paths via local /dev/kvm ioctls (KVM_CREATE_VM, KVM_CREATE_VCPU, KVM_RUN) from L1; there is no network, adjacent, or physical packet/device path to the vulnerable code.\nAC:L - An L1 attacker fully controls nested VM configuration (x2APIC, AVIC, L2 MSR bitmap, IRQ-window/ExtINT conditions) and can reliably reproduce AVIC inhibition while L2 is active without races or uncontrollable host state.\nPR:H - Reaching the bug requires running nested AMD KVM as L1 (nested virtualization enabled and control of a guest hypervisor), which is not available to an unprivileged host user or via user-namespace capabilities alone without delegated /dev/kvm access.\nUI:N - No victim interaction is required; exploitation is driven entirely by the attacker\u2019s nested hypervisor configuration and KVM_RUN operations once nested virtualization is available.\nS:C - The flaw lets an L1 nested guest hypervisor access the host\u2019s physical x2APIC MSRs, crossing the VM/host security boundary rather than staying within the guest\u2019s own security scope.\nC:H - With x2APIC MSR intercepts left disabled, L1 can read most of the host APIC state (IDs, IRR/ISR, timers, ICR), leaking sensitive host interrupt-controller information beyond the guest boundary.\nI:H - L1 can write host x2APIC MSRs to send arbitrary IPIs, change task priority, and invoke host interrupt vectors (e.g. posted-interrupt wakeup), enabling host integrity compromise beyond mere guest-local effects.\nA:H - Host availability is trivially impacted by injecting spurious or high-priority interrupts to host CPUs; the fix commit demonstrates host kernel warnings and spurious interrupt storms causing denial of service."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/x86/kvm/svm/avic.c"], "versions": [{"version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "4ca05385b3ddbd463be17c6d69ec76fca657081d", "status": "affected", "versionType": "git"}, {"version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "6664a5aea45318f4ec156a729949b474dd6e3159", "status": "affected", "versionType": "git"}, {"version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "f12373625b4dc9bcc89c41872648878c73bb9272", "status": "affected", "versionType": "git"}, {"version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "7668c58dcf465559dc7a0d2e95e9cb79cf47454b", "status": "affected", "versionType": "git"}, {"version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "89f9e8398e79c49886766fc24a84c37726231104", "status": "affected", "versionType": "git"}, {"version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "7d3aae206663c4e006b25a1c7a20a4029e67da76", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/x86/kvm/svm/avic.c"], "versions": [{"version": "6.0", "status": "affected"}, {"version": "0", "lessThan": "6.0", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.151", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.103", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.44", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.8", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.1.183"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.6.151"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.12.103"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.18.44"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "7.1.8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/4ca05385b3ddbd463be17c6d69ec76fca657081d"}, {"url": "https://git.kernel.org/stable/c/6664a5aea45318f4ec156a729949b474dd6e3159"}, {"url": "https://git.kernel.org/stable/c/f12373625b4dc9bcc89c41872648878c73bb9272"}, {"url": "https://git.kernel.org/stable/c/7668c58dcf465559dc7a0d2e95e9cb79cf47454b"}, {"url": "https://git.kernel.org/stable/c/89f9e8398e79c49886766fc24a84c37726231104"}, {"url": "https://git.kernel.org/stable/c/7d3aae206663c4e006b25a1c7a20a4029e67da76"}], "title": "KVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-74516", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T18:58:50.382983Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:05:52.090Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-74516", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T18:58:50.382983Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T18:58:51.191Z"}}], "cna": {"title": "KVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 8.2, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:L - Exploitation requires triggering KVM nested SVM/AVIC paths via local /dev/kvm ioctls (KVM_CREATE_VM, KVM_CREATE_VCPU, KVM_RUN) from L1; there is no network, adjacent, or physical packet/device path to the vulnerable code.\nAC:L - An L1 attacker fully controls nested VM configuration (x2APIC, AVIC, L2 MSR bitmap, IRQ-window/ExtINT conditions) and can reliably reproduce AVIC inhibition while L2 is active without races or uncontrollable host state.\nPR:H - Reaching the bug requires running nested AMD KVM as L1 (nested virtualization enabled and control of a guest hypervisor), which is not available to an unprivileged host user or via user-namespace capabilities alone without delegated /dev/kvm access.\nUI:N - No victim interaction is required; exploitation is driven entirely by the attacker\u2019s nested hypervisor configuration and KVM_RUN operations once nested virtualization is available.\nS:C - The flaw lets an L1 nested guest hypervisor access the host\u2019s physical x2APIC MSRs, crossing the VM/host security boundary rather than staying within the guest\u2019s own security scope.\nC:H - With x2APIC MSR intercepts left disabled, L1 can read most of the host APIC state (IDs, IRR/ISR, timers, ICR), leaking sensitive host interrupt-controller information beyond the guest boundary.\nI:H - L1 can write host x2APIC MSRs to send arbitrary IPIs, change task priority, and invoke host interrupt vectors (e.g. posted-interrupt wakeup), enabling host integrity compromise beyond mere guest-local effects.\nA:H - Host availability is trivially impacted by injecting spurious or high-priority interrupts to host CPUs; the fix commit demonstrates host kernel warnings and spurious interrupt storms causing denial of service."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "4ca05385b3ddbd463be17c6d69ec76fca657081d", "versionType": "git"}, {"status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "6664a5aea45318f4ec156a729949b474dd6e3159", "versionType": "git"}, {"status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "f12373625b4dc9bcc89c41872648878c73bb9272", "versionType": "git"}, {"status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "7668c58dcf465559dc7a0d2e95e9cb79cf47454b", "versionType": "git"}, {"status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "89f9e8398e79c49886766fc24a84c37726231104", "versionType": "git"}, {"status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "lessThan": "7d3aae206663c4e006b25a1c7a20a4029e67da76", "versionType": "git"}], "programFiles": ["arch/x86/kvm/svm/avic.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "6.0"}, {"status": "unaffected", "version": "0", "lessThan": "6.0", "versionType": "semver"}, {"status": "unaffected", "version": "6.1.183", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.151", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.103", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.44", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "7.1.8", "versionType": "semver", "lessThanOrEqual": "7.1.*"}, {"status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["arch/x86/kvm/svm/avic.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/4ca05385b3ddbd463be17c6d69ec76fca657081d"}, {"url": "https://git.kernel.org/stable/c/6664a5aea45318f4ec156a729949b474dd6e3159"}, {"url": "https://git.kernel.org/stable/c/f12373625b4dc9bcc89c41872648878c73bb9272"}, {"url": "https://git.kernel.org/stable/c/7668c58dcf465559dc7a0d2e95e9cb79cf47454b"}, {"url": "https://git.kernel.org/stable/c/89f9e8398e79c49886766fc24a84c37726231104"}, {"url": "https://git.kernel.org/stable/c/7d3aae206663c4e006b25a1c7a20a4029e67da76"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active\n\nAlways update x2APIC MSR intercepts for L1 when AVIC is deactivated, even\nif L2 is active and KVM is using a separate MSR bitmap to run L2. If AVIC\nis fully enabled prior to running L2, and is then inhibited while L2 is\nactive (for a VM-scoped inhibit), then KVM will run L1 with AVIC disabled,\nbut with x2APIC MSR intercepts disabled, i.e. will allow L1 to read most of\nthe host's APIC state, send arbitrary interrupts, change task priority, and\nultimately trivially DoS the host.\n\nE.g. sending a self-IPI in L1 on HYPERV_REENLIGHTENMENT_VECTOR, 0xee, with\nCONFIG_HYPERV=n in the host kernel as a \"safe\" PoC, yields:\n\n Spurious interrupt (vector 0xee) on CPU#425. Acked\n\nAnd hacking KVM to abuse kvm_set_posted_intr_wakeup_handler() to register a\nhandler and WARN on POSTED_INTR_WAKEUP_VECTOR yields:\n\n ------------[ cut here ]------------\n WARNING: arch/x86/kvm/svm/svm.c:5594 at pi_wakeup_handler+0x9/0x10 [kvm_amd], CPU#156: nested_x2apic_t/316940\n CPU: 156 UID: 0 PID: 316940 Comm: nested_x2apic_t Tainted: G S U\n Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER\n Hardware name: Google Astoria-Turin/astoria, BIOS 0.20260209.0-0 02/09/2026\n RIP: 0010:pi_wakeup_handler+0x9/0x10 [kvm_amd]\n Call Trace:\n <IRQ>\n sysvec_kvm_posted_intr_wakeup_ipi+0x64/0x80\n </IRQ>\n <TASK>\n asm_sysvec_kvm_posted_intr_wakeup_ipi+0x1a/0x20\n RIP: 0010:vcpu_run+0x1430/0x1e40 [kvm]\n kvm_arch_vcpu_ioctl_run+0x2c1/0x600 [kvm]\n kvm_vcpu_ioctl+0x580/0x6b0 [kvm]\n __se_sys_ioctl+0x6d/0xb0\n do_syscall_64+0x10a/0x480\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x46ff4b\n </TASK>\n ---[ end trace 0000000000000000 ]---"}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.183", "versionStartIncluding": "6.0"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.151", "versionStartIncluding": "6.0"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.103", "versionStartIncluding": "6.0"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18.44", "versionStartIncluding": "6.0"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.1.8", "versionStartIncluding": "6.0"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.2", "versionStartIncluding": "6.0"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-19T16:38:16.902Z"}}}, "cveMetadata": {"cveId": "CVE-2026-74516", "state": "PUBLISHED", "dateUpdated": "2026-10-16T19:05:52.090Z", "dateReserved": "2026-08-15T05:44:03.910Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2026-08-15T12:27:36.200Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["arch/x86/kvm/svm/avic.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "4ca05385b3ddbd463be17c6d69ec76fca657081d", "status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "versionType": "git"}, {"lessThan": "6664a5aea45318f4ec156a729949b474dd6e3159", "status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "versionType": "git"}, {"lessThan": "f12373625b4dc9bcc89c41872648878c73bb9272", "status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "versionType": "git"}, {"lessThan": "7668c58dcf465559dc7a0d2e95e9cb79cf47454b", "status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "versionType": "git"}, {"lessThan": "89f9e8398e79c49886766fc24a84c37726231104", "status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "versionType": "git"}, {"lessThan": "7d3aae206663c4e006b25a1c7a20a4029e67da76", "status": "affected", "version": "091abbf578f926e763adc0f577baeb7f405b4bdc", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["arch/x86/kvm/svm/avic.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.0"}, {"lessThan": "6.0", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.183", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.151", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.103", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.44", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.8", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active\n\nAlways update x2APIC MSR intercepts for L1 when AVIC is deactivated, even\nif L2 is active and KVM is using a separate MSR bitmap to run L2. If AVIC\nis fully enabled prior to running L2, and is then inhibited while L2 is\nactive (for a VM-scoped inhibit), then KVM will run L1 with AVIC disabled,\nbut with x2APIC MSR intercepts disabled, i.e. will allow L1 to read most of\nthe host's APIC state, send arbitrary interrupts, change task priority, and\nultimately trivially DoS the host.\n\nE.g. sending a self-IPI in L1 on HYPERV_REENLIGHTENMENT_VECTOR, 0xee, with\nCONFIG_HYPERV=n in the host kernel as a \"safe\" PoC, yields:\n\n Spurious interrupt (vector 0xee) on CPU#425. Acked\n\nAnd hacking KVM to abuse kvm_set_posted_intr_wakeup_handler() to register a\nhandler and WARN on POSTED_INTR_WAKEUP_VECTOR yields:\n\n ------------[ cut here ]------------\n WARNING: arch/x86/kvm/svm/svm.c:5594 at pi_wakeup_handler+0x9/0x10 [kvm_amd], CPU#156: nested_x2apic_t/316940\n CPU: 156 UID: 0 PID: 316940 Comm: nested_x2apic_t Tainted: G S U\n Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER\n Hardware name: Google Astoria-Turin/astoria, BIOS 0.20260209.0-0 02/09/2026\n RIP: 0010:pi_wakeup_handler+0x9/0x10 [kvm_amd]\n Call Trace:\n <IRQ>\n sysvec_kvm_posted_intr_wakeup_ipi+0x64/0x80\n </IRQ>\n <TASK>\n asm_sysvec_kvm_posted_intr_wakeup_ipi+0x1a/0x20\n RIP: 0010:vcpu_run+0x1430/0x1e40 [kvm]\n kvm_arch_vcpu_ioctl_run+0x2c1/0x600 [kvm]\n kvm_vcpu_ioctl+0x580/0x6b0 [kvm]\n __se_sys_ioctl+0x6d/0xb0\n do_syscall_64+0x10a/0x480\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x46ff4b\n </TASK>\n ---[ end trace 0000000000000000 ]---"}], "id": "CVE-2026-74516", "lastModified": "2026-10-16T20:17:34.160", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 8.2, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "HIGH", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.5, "impactScore": 6.0, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-74516", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T18:58:50.382983Z", "version": "2.0.3"}}]}, "published": "2026-08-15T13:17:56.737", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4ca05385b3ddbd463be17c6d69ec76fca657081d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6664a5aea45318f4ec156a729949b474dd6e3159"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7668c58dcf465559dc7a0d2e95e9cb79cf47454b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7d3aae206663c4e006b25a1c7a20a4029e67da76"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/89f9e8398e79c49886766fc24a84c37726231104"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f12373625b4dc9bcc89c41872648878c73bb9272"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: KVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active", "id": "2516998", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2516998"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-266", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nKVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active\nAlways update x2APIC MSR intercepts for L1 when AVIC is deactivated, even\nif L2 is active and KVM is using a separate MSR bitmap to run L2. If AVIC\nis fully enabled prior to running L2, and is then inhibited while L2 is\nactive (for a VM-scoped inhibit), then KVM will run L1 with AVIC disabled,\nbut with x2APIC MSR intercepts disabled, i.e. will allow L1 to read most of\nthe host's APIC state, send arbitrary interrupts, change task priority, and\nultimately trivially DoS the host.\nE.g. sending a self-IPI in L1 on HYPERV_REENLIGHTENMENT_VECTOR, 0xee, with\nCONFIG_HYPERV=n in the host kernel as a \"safe\" PoC, yields:\nSpurious interrupt (vector 0xee) on CPU#425. Acked\nAnd hacking KVM to abuse kvm_set_posted_intr_wakeup_handler() to register a\nhandler and WARN on POSTED_INTR_WAKEUP_VECTOR yields:\n------------[ cut here ]------------\nWARNING: arch/x86/kvm/svm/svm.c:5594 at pi_wakeup_handler+0x9/0x10 [kvm_amd], CPU#156: nested_x2apic_t/316940\nCPU: 156 UID: 0 PID: 316940 Comm: nested_x2apic_t Tainted: G S U\nTainted: [S]=CPU_OUT_OF_SPEC, [U]=USER\nHardware name: Google Astoria-Turin/astoria, BIOS 0.20260209.0-0 02/09/2026\nRIP: 0010:pi_wakeup_handler+0x9/0x10 [kvm_amd]\nCall Trace:\n<IRQ>\nsysvec_kvm_posted_intr_wakeup_ipi+0x64/0x80\n</IRQ>\n<TASK>\nasm_sysvec_kvm_posted_intr_wakeup_ipi+0x1a/0x20\nRIP: 0010:vcpu_run+0x1430/0x1e40 [kvm]\nkvm_arch_vcpu_ioctl_run+0x2c1/0x600 [kvm]\nkvm_vcpu_ioctl+0x580/0x6b0 [kvm]\n__se_sys_ioctl+0x6d/0xb0\ndo_syscall_64+0x10a/0x480\nentry_SYSCALL_64_after_hwframe+0x4b/0x53\nRIP: 0033:0x46ff4b\n</TASK>\n---[ end trace 0000000000000000 ]---", "A flaw was found in KVM (Kernel-based Virtual Machine). When the Advanced Virtual Interrupt Controller (AVIC) is inhibited while a nested guest (L2) is active, KVM fails to properly update x2APIC MSR intercepts for the primary guest (L1). This allows the L1 guest to read the host's APIC state, send arbitrary interrupts, and change task priority, ultimately leading to a Denial of Service (DoS) of the host system."], "name": "CVE-2026-74516", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-15T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-74516\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-74516\nhttps://lore.kernel.org/linux-cve-announce/2026081543-CVE-2026-74516-6af5@gregkh/T"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[091abbf578f926e763adc0f577baeb7f405b4bdc,6664a5aea45318f4ec156a729949b474dd6e3159)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[091abbf578f926e763adc0f577baeb7f405b4bdc,f12373625b4dc9bcc89c41872648878c73bb9272)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[091abbf578f926e763adc0f577baeb7f405b4bdc,7668c58dcf465559dc7a0d2e95e9cb79cf47454b)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[091abbf578f926e763adc0f577baeb7f405b4bdc,89f9e8398e79c49886766fc24a84c37726231104)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[091abbf578f926e763adc0f577baeb7f405b4bdc,7d3aae206663c4e006b25a1c7a20a4029e67da76)"}}], "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": "generic", "value": "6.0"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.151,7.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.103,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.44,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1.8,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2-rc6,*]"}}], "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": "2026-08-15T14:45:03.921770+00:00", "updated": "2026-08-22T02:00:17.894180+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"], "weaknesses": ["CWE-284", "CWE-200", "CWE-266"]}