{"id":"AZL-57959","summary":"CVE-2025-21779 affecting package kernel for versions less than 6.6.79.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: Reject Hyper-V's SEND_IPI hypercalls if local APIC isn't in-kernel\n\nAdvertise support for Hyper-V's SEND_IPI and SEND_IPI_EX hypercalls if and\nonly if the local API is emulated/virtualized by KVM, and explicitly reject\nsaid hypercalls if the local APIC is emulated in userspace, i.e. don't rely\non userspace to opt-in to KVM_CAP_HYPERV_ENFORCE_CPUID.\n\nRejecting SEND_IPI and SEND_IPI_EX fixes a NULL-pointer dereference if\nHyper-V enlightenments are exposed to the guest without an in-kernel local\nAPIC:\n\n  dump_stack+0xbe/0xfd\n  __kasan_report.cold+0x34/0x84\n  kasan_report+0x3a/0x50\n  __apic_accept_irq+0x3a/0x5c0\n  kvm_hv_send_ipi.isra.0+0x34e/0x820\n  kvm_hv_hypercall+0x8d9/0x9d0\n  kvm_emulate_hypercall+0x506/0x7e0\n  __vmx_handle_exit+0x283/0xb60\n  vmx_handle_exit+0x1d/0xd0\n  vcpu_enter_guest+0x16b0/0x24c0\n  vcpu_run+0xc0/0x550\n  kvm_arch_vcpu_ioctl_run+0x170/0x6d0\n  kvm_vcpu_ioctl+0x413/0xb20\n  __se_sys_ioctl+0x111/0x160\n  do_syscal1_64+0x30/0x40\n  entry_SYSCALL_64_after_hwframe+0x67/0xd1\n\nNote, checking the sending vCPU is sufficient, as the per-VM irqchip_mode\ncan't be modified after vCPUs are created, i.e. if one vCPU has an\nin-kernel local APIC, then all vCPUs have an in-kernel local APIC.","modified":"2026-04-01T05:19:15.106995Z","published":"2025-02-27T03:15:18Z","upstream":["CVE-2025-21779"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21779"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.79.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-57959.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}