NULL pointer dereference in Linux
CVE-2025-21779
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.002 (13.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 13.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
- Linux — versions 214ff83d4473a7757fa18a64dc7efe3b0e158486, 4.20, 0
- Linux Kernel — versions 6.14
Weakness classification (CWE)
Public proof-of-concept exploits
References
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch, Mailing List)
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch, Mailing List)
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch, Mailing List)
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch, Mailing List)
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch, Mailing List)
- af854a3a-2127-422b-91ae-364da2661108
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-21779?
- CVE-2025-21779 is a medium-severity vulnerability in Linux, classified under NULL Pointer Dereference. CVSS score: 5.5/10. Published 2025-02-27.
- How severe is CVE-2025-21779?
- Medium severity. CVSS v3 base score is 5.5 out of 10.
- Is CVE-2025-21779 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.