CVE-2026-90243: Linux kernel · iommu/vt-d: Clear Present bit before tearing down copied context entry
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 8.1 High.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 17 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available that implements the proper sequence of clearing the Present bit before zeroing the context entry and performing invalidations as per the VT-d specification. Users should apply the official Linux kernel updates that address this issue in the affected versions. No additional mitigations are indicated.
Description
A vulnerability in the Linux kernel's iommu/vt-d component was resolved where the Present bit was not cleared before tearing down a copied context entry. This flaw could lead to hardware fetching a partially zeroed context entry while the Present bit remained set, causing unpredictable behavior or spurious faults. The issue arises due to potential write reordering and lack of cacheline flush before invalidation. The fix involves clearing the Present bit first, flushing it to the IOMMU, performing invalidations, and then zeroing the rest of the entry.
References
- nvd.nist.gov/vuln/detail/CVE-2026-90243 (opens in a new tab)
- git.kernel.org/stable/c/3c88cfedc7768b1ae2dc7ddc71547ae9a1aaff7d (opens in a new tab)
- git.kernel.org/stable/c/6b822d18c33af9d1e16a8e5e6aa6e656987b09de (opens in a new tab)
- git.kernel.org/stable/c/97750a8dce79c1a9b2b2d2a020b61b800141996c (opens in a new tab)
- git.kernel.org/stable/c/f532c57985b1a7d6b7e37e05506b46d413e5cca4 (opens in a new tab)
- ubuntu.com/security/CVE-2026-90243 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-90243 (opens in a new tab)
- git.kernel.org/linus/f532c57985b1a7d6b7e37e05506b46d413e5cca4 (opens in a new tab)