Vulnerability in Linux Kernel Affecting Stream ID Mapping for vDEVICEs

CVE-2026-74573

What is CVE-2026-74573?

In the Linux kernel, a flaw exists within the iommu/arm-smmu-v3-iommufd module. This vulnerability arises when a device with multiple streams is mapped, causing the system to mismanage Stream IDs. Specifically, the mapping process assumes that each device has only one Stream ID, leading to a potential failure in guest vSID invalidation and exposing the system to out-of-bounds read issues. To mitigate this, an enhancement has been introduced that requires verification of the number of streams before permitting the mapping of a vDEVICE. If the number of streams is not set to one, the operation will not proceed, thus improving the robustness of the system against potential crashes or unauthorized access.

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