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CVE Record

CVE-2026-46034: vfio/cdx: Fix NULL pointer dereference in interrupt trigger path

In the Linux kernel, the following vulnerability has been resolved: vfio/cdx: Fix NULL pointer dereference in interrupt trigger path Add validation to ensure MSI is configured before accessing cdx_irqs array in vfio_cdx_set_msi_trigger(). Without this check, userspace can trigger a NULL pointer dereference by calling VFIO_DEVICE_SET_IRQS with VFIO_IRQ_SET_DATA_BOOL or VFIO_IRQ_SET_DATA_NONE flags before ever setting up interrupts via VFIO_IRQ_SET_DATA_EVENTFD. The vfio_cdx_msi_enable() function allocates the cdx_irqs array and sets config_msi to 1 only when called through the EVENTFD path. The trigger loop (for DATA_BOOL/DATA_NONE) assumed this had already been done, but there was no enforcement of this call ordering. This matches the protection used in the PCI VFIO driver where vfio_pci_set_msi_trigger() checks irq_is() before the trigger loop.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-46034 is a Linux kernel flaw in the vfio/cdx driver. A userspace caller can hit a NULL pointer dereference by triggering MSI interrupts before they are configured. The likely business impact is host stability risk on systems using this VFIO CDX path, not confirmed remote compromise.

Executive priority

Treat this as a targeted kernel stability issue. Prioritize patching systems that expose VFIO CDX to userspace workloads or tenants. Broad emergency action is not supported by the provided evidence because there is no KEV listing, CVSS score, or active exploitation claim.

Technical view

The bug is in vfio_cdx_set_msi_trigger(). DATA_BOOL or DATA_NONE handling could access the cdx_irqs array before vfio_cdx_msi_enable() allocated it through the EVENTFD path and set config_msi. The fix adds validation that MSI is configured before the trigger loop, aligning behavior with the PCI VFIO driver.

Likely exposure

Exposure appears limited to Linux systems with affected kernels and vfio/cdx in use, especially where userspace workloads can access VFIO CDX devices. The bundle lists Linux kernel versions and stable commits, but does not provide distribution-specific package names or configuration prerequisites.

Exploitation context

The source states userspace can trigger the NULL pointer dereference through VFIO_DEVICE_SET_IRQS ordering. KEV is false, and the bundle provides no evidence of active exploitation, public exploit tooling, or remote attack paths.

Researcher notes

Evidence is specific but incomplete. The CVE describes the vulnerable call ordering and fix rationale, but provides no CVSS, CWE, exploit status, or distro mapping. Version data in the bundle is difficult to interpret, so validate exposure against kernel commits and vendor advisories.

Mitigation direction

  • Update to a kernel containing the referenced stable vfio/cdx fixes.
  • Check Linux distribution advisories for fixed package versions.
  • Restrict VFIO CDX device access to trusted users and workloads.
  • Prioritize hosts running virtualization or device-passthrough workflows using CDX.
  • Monitor vendor guidance for any severity or backport changes.

Validation and detection

  • Inventory running kernel versions on systems using VFIO CDX.
  • Confirm whether vfio/cdx is enabled or loaded on relevant hosts.
  • Verify the fixed stable commit or vendor backport is present.
  • Review which users or workloads can access VFIO devices.
  • Regression-test device passthrough workflows after kernel update.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2026-46034 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
5Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux848e447e000c41894ff931dc7c004fd42c8840f8, 848e447e000c41894ff931dc7c004fd42c8840f8, 848e447e000c41894ff931dc7c004fd42c8840f8, 848e447e000c41894ff931dc7c004fd42c8840f8unaffected
LinuxLinux6.10, 0, 6.12.86, 6.18.27, 7.0.4, 7.1affected
Weakness

CWE details

No CWE listed

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