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CVE-2026-46295— KVM: x86: Do IRR scan in __kvm_apic_update_irr even if PIR is empty

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于KVM中IRR扫描竞争条件，可能导致系统崩溃。

AI Predicted 5.5 Difficulty: Trivial EPSS 0.16% · P5

Possible ATT&CK Techniques 1 AI

T1498.001 · Direct Network Flood

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux b41f8638b9d30fbe045b4ef83ff4136c56a57397< bb1703949dcaa9a49c338dee075f659f4634214d affected
b41f8638b9d30fbe045b4ef83ff4136c56a57397< 4b6b06a8b12bfd95f9015074b1430c1480908073 affected
b41f8638b9d30fbe045b4ef83ff4136c56a57397< 33fd0ccd2590b470b65adcca288615ad3b5e3e06 affected
6.16 affected
< 6.16 unaffected
6.18.30≤ 6.18.* unaffected
7.0.7≤ 7.0.* unaffected
7.1≤ * unaffected
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I. Basic Information for CVE-2026-46295

Vulnerability Information
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Vulnerability Title
KVM: x86: Do IRR scan in __kvm_apic_update_irr even if PIR is empty
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于KVM中IRR扫描竞争条件，可能导致系统崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux b41f8638b9d30fbe045b4ef83ff4136c56a57397 ~ bb1703949dcaa9a49c338dee075f659f4634214d -
Linux Linux 6.16 -

II. Public POCs for CVE-2026-46295

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III. Intelligence Information for CVE-2026-46295

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Patches & Fixes for CVE-2026-46295 (3)

Same Patch Batch · Linux · 2026-06-08 · 41 CVEs total

CVE-2026-46289 9.8 CRITICAL lib/scatterlist: fix length calculations in extract_kvec_to_sg
CVE-2026-46288 8.4 HIGH of: unittest: fix use-after-free in of_unittest_changeset()
CVE-2026-46307 8.3 HIGH wifi: ath5k: do not access array OOB
CVE-2026-46303 8.2 HIGH isofs: validate Rock Ridge CE continuation extent against volume size
CVE-2026-46274 7.8 HIGH io-wq: check that the predecessor is hashed in io_wq_remove_pending()
CVE-2026-46275 7.8 HIGH Bluetooth: hci_uart: fix UAFs and race conditions in close and init paths
CVE-2026-46277 7.8 HIGH mm/zone_device: do not touch device folio after calling ->folio_free()
CVE-2026-46280 7.8 HIGH lib: test_hmm: evict device pages on file close to avoid use-after-free
CVE-2026-46311 7.8 HIGH drm/amdgpu/userq: fix access to stale wptr mapping
CVE-2026-46304 7.5 HIGH nvmet: avoid recursive nvmet-wq flush in nvmet_ctrl_free
CVE-2026-46306 7.5 HIGH flow_dissector: do not dissect PPPoE PFC frames
CVE-2026-46299 7.0 HIGH hfsplus: fix held lock freed on hfsplus_fill_super()
CVE-2026-46298 pseries/papr-hvpipe: Fix race with interrupt handler
CVE-2026-46314 drm/v3d: Reject empty multisync extension to prevent infinite loop
CVE-2026-46301 spi: topcliff-pch: fix use-after-free on unbind
CVE-2026-46302 selinux: allow multiple opens of /sys/fs/selinux/policy
CVE-2026-46305 staging: rtl8723bs: os_dep: avoid NULL pointer dereference in rtw_cbuf_alloc
CVE-2026-46308 pmdomain: mediatek: fix use-after-free in scpsys_get_bus_protection_legacy()
CVE-2026-46309 drm/xe/uapi: Reject coh_none PAT index for CPU cached memory in madvise
CVE-2026-46310 media: renesas: vsp1: Fix NULL pointer deref on module unload

Showing top 20 of 41 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-46295

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