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CVE-2026-46295 Linux CVE debrief

A vulnerability was found in the Linux kernel, specifically in the KVM x86 module. The vulnerability occurs when the IRR scan is not performed correctly in the __kvm_apic_update_irr function, even if the PIR is empty. This can lead to a spurious WARNING and a wasted L2 VM-Enter/VM-Exit cycle. The root cause of the issue is a race between vmx_sync_pir_to_irr() on the target vCPU and __vmx_deliver_posted_interrupt() on a sender vCPU.

Vendor
Linux
Product
Unknown
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-08
Original CVE updated
2026-07-23
Advisory published
2026-06-08
Advisory updated
2026-07-23

Who should care

Users of the Linux kernel, specifically those using KVM x86, should be aware of this vulnerability. This vulnerability may allow for a denial of service (DoS) attack.

Technical summary

The vulnerability occurs in the __kvm_apic_update_irr function, where the IRR scan is not performed correctly when the PIR is empty. This can lead to a spurious WARNING and a wasted L2 VM-Enter/VM-Exit cycle. The root cause of the issue is a race between vmx_sync_pir_to_irr() on the target vCPU and __vmx_deliver_posted_interrupt() on a sender vCPU.

Defensive priority

High

Recommended defensive actions

  • Update the Linux kernel to the latest version
  • Apply the patches provided by the Linux kernel maintainers

Evidence notes

The vulnerability was resolved by falling 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.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-46295 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-46295

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-46295 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-46295

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/33fd0ccd2590b470b65adcca288615ad3b5e3e06

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/4b6b06a8b12bfd95f9015074b1430c1480908073

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/bb1703949dcaa9a49c338dee075f659f4634214d

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.