{"id":"DEBIAN-CVE-2025-21779","details":"In the Linux kernel, the following vulnerability has been resolved:  KVM: x86: Reject Hyper-V's SEND_IPI hypercalls if local APIC isn't in-kernel  Advertise support for Hyper-V's SEND_IPI and SEND_IPI_EX hypercalls if and only if the local API is emulated/virtualized by KVM, and explicitly reject said hypercalls if the local APIC is emulated in userspace, i.e. don't rely on userspace to opt-in to KVM_CAP_HYPERV_ENFORCE_CPUID.  Rejecting SEND_IPI and SEND_IPI_EX fixes a NULL-pointer dereference if Hyper-V enlightenments are exposed to the guest without an in-kernel local APIC:    dump_stack+0xbe/0xfd   __kasan_report.cold+0x34/0x84   kasan_report+0x3a/0x50   __apic_accept_irq+0x3a/0x5c0   kvm_hv_send_ipi.isra.0+0x34e/0x820   kvm_hv_hypercall+0x8d9/0x9d0   kvm_emulate_hypercall+0x506/0x7e0   __vmx_handle_exit+0x283/0xb60   vmx_handle_exit+0x1d/0xd0   vcpu_enter_guest+0x16b0/0x24c0   vcpu_run+0xc0/0x550   kvm_arch_vcpu_ioctl_run+0x170/0x6d0   kvm_vcpu_ioctl+0x413/0xb20   __se_sys_ioctl+0x111/0x160   do_syscal1_64+0x30/0x40   entry_SYSCALL_64_after_hwframe+0x67/0xd1  Note, checking the sending vCPU is sufficient, as the per-VM irqchip_mode can't be modified after vCPUs are created, i.e. if one vCPU has an in-kernel local APIC, then all vCPUs have an in-kernel local APIC.","modified":"2026-09-01T16:06:10.254878771Z","published":"2025-02-27T03:15:18.690Z","upstream":["CVE-2025-21779"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2025-21779"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.129-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21779.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.16-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21779.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.16-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21779.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}