CVE-2026-74573

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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\u2014an 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"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-74573", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T19:00:36.894843Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:05:56.969Z"}}]}}

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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."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18.44", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.1.8", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.2", "versionStartIncluding": "6.13"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:48:52.745Z"}}}, "cveMetadata": {"cveId": "CVE-2026-74573", "state": "PUBLISHED", "dateUpdated": "2026-10-16T19:05:56.969Z", "dateReserved": "2026-08-15T05:44:03.917Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2026-08-15T12:28:11.935Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "3808bab5d95ae79e333e11f6a73d178e084c645d", "status": "affected", "version": "d68beb276ba26cec47350a6d468e967673ee0c56", "versionType": "git"}, {"lessThan": "0acbc621341aca4eb94d9c2f43e1ab273ff088f0", "status": "affected", "version": "d68beb276ba26cec47350a6d468e967673ee0c56", "versionType": "git"}, {"lessThan": "c3b8ee84a965058b41275069d4696f37a8b14bf6", "status": "affected", "version": "d68beb276ba26cec47350a6d468e967673ee0c56", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.13"}, {"lessThan": "6.13", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.44", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.8", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "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."}], "id": "CVE-2026-74573", "lastModified": "2026-10-16T20:17:38.797", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 9.3, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.5, "impactScore": 6.0, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-74573", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T19:00:36.894843Z", "version": "2.0.3"}}]}, "published": "2026-08-15T13:18:02.963", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0acbc621341aca4eb94d9c2f43e1ab273ff088f0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/3808bab5d95ae79e333e11f6a73d178e084c645d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/c3b8ee84a965058b41275069d4696f37a8b14bf6"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: iommu/arm-smmu-v3-iommufd: Require exactly one Stream ID for a vDEVICE", "id": "2517091", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2517091"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-823", "details": ["A flaw was found in the Linux kernel's ARM System Memory Management Unit version 3 (SMMUv3) IOMMU driver. This vulnerability occurs because the driver incorrectly assumes that a virtual device (vDEVICE) has only one Stream ID. This can lead to a guest operating system's virtual Stream ID invalidation failing to clear all relevant entries, potentially resulting in information disclosure or data integrity issues. Additionally, if a virtual device has no streams, an out-of-bounds read can occur, which may lead to a denial of service."], "name": "CVE-2026-74573", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-15T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-74573\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-74573\nhttps://lore.kernel.org/linux-cve-announce/2026081555-CVE-2026-74573-d1e9@gregkh/T"], "threat_severity": "Important"}

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