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CVE-2026-45945 Linux CVE debrief

A race condition in the Linux kernel's Intel VT-d IOMMU driver could allow torn reads of PASID table entries, potentially causing unpredictable IOMMU behavior or spurious faults. The vulnerability exists because the kernel performed atomic 512-bit structure assignments to active PASID entries without ensuring hardware-consistent updates. The fix implements a clear-then-update flow with proper invalidation handshakes.

Vendor
Linux
Product
Unknown
CVSS
HIGH 8.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-27
Original CVE updated
2026-07-18
Advisory published
2026-05-27
Advisory updated
2026-07-18

Who should care

Organizations running Linux systems with Intel VT-d enabled, particularly virtualization platforms using device assignment with PASID capabilities. Cloud providers and enterprises with PCI device passthrough configurations should monitor for kernel updates.

Technical summary

The Intel VT-d implementation in the Linux kernel contains a race condition when replacing active PASID (Process Address Space ID) table entries. The 512-bit PASID entry structure was being updated via direct assignment while the Present bit remained set, creating a window where the IOMMU hardware could perform partial 128-bit chunk reads of inconsistent data. This torn read scenario could produce undefined IOMMU translation behavior. The resolution removes unsafe replacement helpers and enforces a two-phase clear-then-update protocol with mandatory cache invalidation between phases, ensuring hardware-observable atomicity.

Defensive priority

medium

Recommended defensive actions

  • Apply kernel updates containing commits 66a7aff480a8 and c3b1edea3791 when available from your Linux distribution
  • For systems using Intel VT-d with PASID (Process Address Space ID) features, prioritize kernel updates on virtualization hosts and systems with device assignment
  • Monitor distribution security advisories for backported stable kernel updates
  • Review system logs for IOMMU fault messages that may indicate trigger conditions

Evidence notes

CVE published 2026-05-27. Kernel commit references indicate stable branch fixes. No CVSS score assigned by NVD at time of disclosure.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-45945 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-45945

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

  • CVE-2026-45945 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-45945

    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/66a7aff480a82b8642b3991fed5fdc9780022157

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/c3b1edea3791fa91ab7032faa90355913ad9451b

    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.