CVE-2026-90243
HighCVSS 8.1Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
In the Linux kernel's iommu/vt-d subsystem, there is an issue with clearing the Present bit before tearing down a copied context entry. Zeroing the entry while Present is still set leaves a window where hardware can fetch a torn entry, leading to unpredictable behavior or spurious faults.
Risk Assessment
This can lead to system instability, spurious IOMMU faults, and potentially system crashes.
Recommendation
Apply the Linux kernel update containing the fix that clears the Present bit first, performs invalidations, and only then zeroes the remainder of the entry.
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Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS