CVE-2026-46295
Vulnerability Scoring
Status: Received on 08 Jun 2026, 17:16 UTC
Published on: 08 Jun 2026, 17:16 UTC
CVSS Release:
CVE-2026-46295: In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Do IRR scan in __kvm_apic_update_irr even if PIR is empty Fall back to apic_find_highest_vector() when PID.ON is set but PIR turns out to be empty, to correctly report the highest pending interrupt from the existing IRR. In a nested VM stress test, the following WARNING fires in vmx_check_nested_events() when kvm_cpu_has_interrupt() reports a pending interrupt but the subsequent kvm_apic_has_interrupt() (which invokes vmx_sync_pir_to_irr() again) returns -1: WARNING: CPU: 99 PID: 57767 at arch/x86/kvm/vmx/nested.c:4449 vmx_check_nested_events+0x6bf/0x6e0 [kvm_intel] Call Trace: kvm_check_and_inject_events vcpu_enter_guest.constprop.0 vcpu_run kvm_arch_vcpu_ioctl_run kvm_vcpu_ioctl __x64_sys_ioctl do_syscall_64 entry_SYSCALL_64_after_hwframe The root cause is a race between vmx_sync_pir_to_irr() on the target vCPU and __vmx_deliver_posted_interrupt() on a sender vCPU. The sender performs two individually-atomic operations that are not a single transaction: 1. pi_test_and_set_pir(vector) -- sets the PIR bit 2. pi_test_and_set_on() -- sets PID.ON The following interleaving triggers the bug: Sender vCPU (IPI): Target vCPU (1st sync_pir_to_irr): B1: set PIR[vector] A1: pi_clear_on() A2: pi_harvest_pir() -> sees B1 bit A3: xchg() -> consumes bit, PIR=0 (1st sync returns correct max_irr) B2: set PID.ON = 1 Target vCPU (2nd sync_pir_to_irr): C1: pi_test_on() -> TRUE (from B2) C2: pi_clear_on() -> ON=0 C3: pi_harvest_pir() -> PIR empty C4: *max_irr = -1, early return IRR NOT SCANNED The interrupt is not lost (it resides in the IRR from the first sync and is recovered on the next vcpu_enter_guest() iteration), but the incorrect max_irr causes a spurious WARNING and a wasted L2 VM-Enter/VM-Exit cycle.
The exploitability of CVE-2026-46295 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
No exploitability data is available for CVE-2026-46295.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2026-46295, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2026-46295, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
Unknown
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