{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74573","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-15T05:44:03.917Z","datePublished":"2026-08-15T12:28:11.935Z","dateUpdated":"2026-08-17T05:48:52.745Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T05:48:52.745Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/arm-smmu-v3-iommufd: Require exactly one Stream ID for a vDEVICE\n\narm_vsmmu_vsid_to_sid() maps a guest's vSID to a single physical Stream ID\ntaken from master->streams[0], assuming a device has exactly one stream. A\ndevice with several streams gets only its first one mapped, so a guest vSID\ninvalidation cannot reach the others' ATC and IOTLB entries; a device with\nnone makes master->streams a ZERO_SIZE_PTR, read out of bounds.\n\nAdd an arm_vsmmu_vdevice_init() op to reject the vDEVICE with -EOPNOTSUPP\nwhen master->num_streams is not one, rather than mapping it silently."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","baseScore":9.3,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:L - Exploitation requires reaching arm_vsmmu_cache_invalidate() via the IOMMU_HWPT_INVALIDATE ioctl on /dev/iommu (or VFIO-compat fd), a local syscall path from a process or VMM forwarding guest nested-IOMMU invalidations to the host kernel.\nAC:L - Once a vDEVICE is registered on an ARM SMMUv3 vIOMMU with a multi-stream or zero-stream master, the attacker reliably issues ATC_INV/CFGI_CD invalidation commands; no race or uncontrollable memory layout is required beyond having such hardware attached.\nPR:N - A malicious guest or tenant VM with passed-through PCI and nested vIOMMU needs no host root or credentials; QEMU normally forwards guest IOMMU invalidations to host iommufd, reaching the vulnerable code without any host authentication or admin privilege.\nUI:N - Exploitation is fully attacker-driven through iommufd ioctls and does not require any victim user action such as opening files, clicking links, or mounting filesystems beyond the attacker-controlled device setup.\nS:C - Incomplete vSID-to-SID mapping leaves stale ATC/IOTLB entries on additional Stream IDs, allowing device DMA to bypass the guest nested IOMMU policy and reach host physical memory outside the guest security domain—an IOMMU/DMA boundary violation.\nC:H - Stale translations on un-invalidated streams let a malicious guest or local user read host memory via DMA using cached mappings; the num_streams==0 path also performs an out-of-bounds read of master->streams[0].id from ZERO_SIZE_PTR, leaking kernel memory into the SID field.\nI:H - Stale IOTLB/ATC entries enable arbitrary DMA writes to previously mapped host pages, and the leaked/garbage SID from the out-of-bounds streams[0] read can target invalidation at unintended Stream IDs, corrupting IOMMU translation state.\nA:H - The zero-stream case dereferences master->streams[0] when streams is ZERO_SIZE_PTR, which can kernel-oops the host; even without a crash, stale TLB state enables sustained hostile DMA that can destabilize the system."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c"],"versions":[{"version":"d68beb276ba26cec47350a6d468e967673ee0c56","lessThan":"3808bab5d95ae79e333e11f6a73d178e084c645d","status":"affected","versionType":"git"},{"version":"d68beb276ba26cec47350a6d468e967673ee0c56","lessThan":"0acbc621341aca4eb94d9c2f43e1ab273ff088f0","status":"affected","versionType":"git"},{"version":"d68beb276ba26cec47350a6d468e967673ee0c56","lessThan":"c3b8ee84a965058b41275069d4696f37a8b14bf6","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c"],"versions":[{"version":"6.13","status":"affected"},{"version":"0","lessThan":"6.13","status":"unaffected","versionType":"semver"},{"version":"6.18.44","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.8","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.18.44"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"7.1.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/3808bab5d95ae79e333e11f6a73d178e084c645d"},{"url":"https://git.kernel.org/stable/c/0acbc621341aca4eb94d9c2f43e1ab273ff088f0"},{"url":"https://git.kernel.org/stable/c/c3b8ee84a965058b41275069d4696f37a8b14bf6"}],"title":"iommu/arm-smmu-v3-iommufd: Require exactly one Stream ID for a vDEVICE","x_generator":{"engine":"bippy-1.2.0"}}}}