In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Prevent access to vCPU events before init
Another day, another syzkaller bug. KVM erroneously allows userspace to pend vCPU events for a vCPU that hasn't been initialized yet, leading to KVM interpreting a bunch of uninitialized garbage for routing / injecting the exception.
In one case the injection code and the hyp disagree on whether the vCPU has a 32bit EL1 and put the vCPU into an illegal mode for AArch64, tripping the BUG() in exception_target_el() during the next injection:
kernel BUG at arch/arm64/kvm/inject_fault.c:40! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP CPU: 3 UID: 0 PID: 318 Comm: repro Not tainted 6.17.0-rc4-00104-g10fd0285305d #6 PREEMPT Hardware name: linux,dummy-virt (DT) pstate: 21402009 (nzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) pc : exception_target_el+0x88/0x8c lr : pend_serror_exception+0x18/0x13c sp : ffff800082f03a10 x29: ffff800082f03a10 x28: ffff0000cb132280 x27: 0000000000000000 x26: 0000000000000000 x25: ffff0000c2a99c20 x24: 0000000000000000 x23: 0000000000008000 x22: 0000000000000002 x21: 0000000000000004 x20: 0000000000008000 x19: ffff0000c2a99c20 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 00000000200000c0 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : ffff800082f03af8 x7 : 0000000000000000 x6 : 0000000000000000 x5 : ffff800080f621f0 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 000000000040009b x1 : 0000000000000003 x0 : ffff0000c2a99c20 Call trace: exception_target_el+0x88/0x8c (P) kvm_inject_serror_esr+0x40/0x3b4 __kvm_arm_vcpu_set_events+0xf0/0x100 kvm_arch_vcpu_ioctl+0x180/0x9d4 kvm_vcpu_ioctl+0x60c/0x9f4 __arm64_sys_ioctl+0xac/0x104 invoke_syscall+0x48/0x110 el0_svc_common.constprop.0+0x40/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x34/0xf0 el0t_64_sync_handler+0xa0/0xe4 el0t_64_sync+0x198/0x19c Code: f946bc01 b4fffe61 9101e020 17fffff2 (d4210000)
Reject the ioctls outright as no sane VMM would call these before KVM_ARM_VCPU_INIT anyway. Even if it did the exception would've been thrown away by the eventual reset of the vCPU's state.
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade linux | Sep 18, 2026 | Oct 30, 2025 |
| Huawei Euleros 2_0_sp11 | — | Upgrade kernelUpgrade python3-perfUpgrade kernel-tools-libsUpgrade bpftoolUpgrade kernel-toolsUpgrade kernel-abi-stablelists | Mar 17, 2026 | Mar 17, 2026 |
| Huawei Euleros 2_0_sp13 | — | Upgrade bpftoolUpgrade python3-perfUpgrade kernel-tools-libsUpgrade kernel-toolsUpgrade kernelUpgrade kernel-abi-stablelists | Feb 3, 2026 | Feb 2, 2026 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Oct 30, 2025 |
| Ubuntu | — | Upgrade linux-image-6.17.0-14-genericUpgrade linux-image-gcp-64k-6.17Upgrade linux-image-6.17.0-1007-oracle-64kUpgrade linux-image-oracle-64kUpgrade linux-image-generic-64k-6.17Upgrade linux-image-aws-64k-6.17Upgrade linux-image-generic-64kUpgrade linux-image-oracle-64k-6.17Upgrade linux-image-virtual-6.17Upgrade linux-image-azureUpgrade linux-image-gcp-64kUpgrade linux-image-raspiUpgrade linux-image-oem-6.17Upgrade linux-image-gcp-6.17Upgrade linux-image-realtime-6.17Upgrade linux-image-6.17.0-1007-gcp-64kUpgrade linux-image-aws-64kUpgrade linux-image-virtualUpgrade linux-image-6.17.0-14-generic-64kUpgrade linux-image-6.17.0-1011-oemUpgrade linux-image-raspi-6.17Upgrade linux-image-oracleUpgrade linux-image-6.17.0-1007-oracleUpgrade linux-image-generic-6.17Upgrade linux-image-gcpUpgrade linux-image-6.17.0-1008-raspiUpgrade linux-image-aws-6.17Upgrade linux-image-6.17.0-1007-aws-64kUpgrade linux-image-azure-6.17Upgrade linux-image-genericUpgrade linux-image-6.17.0-1007-awsUpgrade linux-image-realtimeUpgrade linux-image-awsUpgrade linux-image-6.17.0-1007-gcpUpgrade linux-image-6.17.0-1006-realtimeUpgrade linux-image-6.17.0-1008-azureUpgrade linux-image-oracle-6.17 | Feb 13, 2026 | Feb 12, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Sep 21, 2026 | Oct 30, 2025 |
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