CVE-2026-89930

9.3 CRITICAL

Published 2026-09-16 · Updated 2026-09-16

AI risk analysis

Summary: This flaw allows an attacker to cause a local TLB flush on a failed nested VM-Enter, potentially leading to information disclosure, integrity issues, and availability problems.
Exploitability: Exploitation requires a malicious guest VM and the ability to trigger a failed nested VM-Enter, making it moderately difficult to exploit.
Blast radius: If exploited, the impact could be severe, affecting the host system's memory and potentially leading to a compromise of the entire system.
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Upgrade to the Linux kernel version 6.1.18 or later.

local-privilege-escalationmemory-leakhypervisor

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

In the Linux kernel, the following vulnerability has been resolved: KVM: nVMX: Service local TLB flushes on failed nested VM-Enter KVM services local TLB flushes on "full" nested VM-Exits (through __nested_vmx_vmexit()), but not if a nested VM-Enter fails (e.g. due to failed VMCS checks in nested_vmx_enter_non_root_mode()). However, it is possible that KVM had queued TLB flushes that need to be performed, even if the nested VM-Enter was not successful. For example, if VPID is disabled for L2 (via nested_vmx_transition_tlb_flush(), or if via the MSR load lists, as the SDM says: If any MSR is being loaded in such a way that would architecturally require a TLB flush, the TLBs are updated so that, after VM entry, the logical processor will not use any translations that were cached before the transition. The SDM is unclear about when the TLB flush should occur, and whether or not a failed VM entry would flush the TLB, so it is safer to always do the TLB flush in this case. More concretely, KVM also updates the last VPID L1 used for L2 in nested_vmx_transition_tlb_flush() (i.e. last_vpid), even if the VM entry ultimately fails. With the current code, KVM could miss a TLB flush if L1 changes L2's VPID, then does a failed VM entry followed by a successful one, as the failed VM entry would update last_vpid but not actually flush the TLB. Servicing local TLB flushes on failed VM entries makes sure that the TLB is always flushed when last_vpid is updated.

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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