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VulnerabilityPublished Updated

CVE-2026-90243: Linux kernel · iommu/vt-d: Clear Present bit before tearing down copied context entry

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 8.1 High.

Data as of 28 Oct 2026, 01:12 UTC

CVSS 3.1 base score
8.1High
How severe the flaw is on the 0–10 CVSS scale.
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 17 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-5.5 – 7.0.0-38.38
23 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1014.14
15 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1003.3 – 7.0.0-1017.17
15 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threatsAffected
  • 7.0.0-1003.3 – 7.0.0-1016.16
9 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1014.14
13 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threatsAffected
  • 7.0.0-1002.3 – 7.0.0-1008.9
6 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Clear Present bit before tearing down copied context entry copied_context_tear_down() zeroes the 128-bit context entry with context_clear_entry() while the Present bit is still set, and only then issues the context-cache and IOTLB invalidations. This leaves a window in which hardware can fetch a torn entry, with some fields already zeroed while Present is still set, leading to unpredictable behaviour or spurious faults. While x86 provides strong write ordering, the compiler may reorder the writes to the two 64-bit halves of the entry, and the hardware fetch is not guaranteed to be atomic with respect to multiple CPU writes. There is no cacheline flush before the invalidation either, so on an IOMMU without coherent access to the context table the zeroed entry may not be visible to hardware at the point the invalidation is submitted. Apply the same ownership handshake described in the VT-d spec, Section 6.5.3.3 ("Guidance to Software for Invalidations"): clear only the Present bit, flush it out to the IOMMU, perform the invalidations, and only then zero the remainder of the entry.

References

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