{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-45894", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-13T15:03:33.083Z", "datePublished": "2026-05-27T12:17:04.866Z", "dateUpdated": "2026-08-05T12:28:39.976Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:28:39.976Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Clear Present bit before tearing down PASID entry\n\nThe Intel VT-d Scalable Mode PASID table entry consists of 512 bits (64\nbytes). When tearing down an entry, the current implementation zeros the\nentire 64-byte structure immediately using multiple 64-bit writes.\n\nSince the IOMMU hardware may fetch these 64 bytes using multiple\ninternal transactions (e.g., four 128-bit bursts), updating or zeroing\nthe entire entry while it is active (P=1) risks a \"torn\" read. If a\nhardware fetch occurs simultaneously with the CPU zeroing the entry, the\nhardware could observe an inconsistent state, leading to unpredictable\nbehavior or spurious faults.\n\nFollow the \"Guidance to Software for Invalidations\" in the VT-d spec\n(Section 6.5.3.3) by implementing the recommended ownership handshake:\n\n1. Clear only the 'Present' (P) bit of the PASID entry.\n2. Use a dma_wmb() to ensure the cleared bit is visible to hardware\n before proceeding.\n3. Execute the required invalidation sequence (PASID cache, IOTLB, and\n Device-TLB flush) to ensure the hardware has released all cached\n references.\n4. Only after the flushes are complete, zero out the remaining fields\n of the PASID entry.\n\nAlso, add a dma_wmb() in pasid_set_present() to ensure that all other\nfields of the PASID entry are visible to the hardware before the Present\nbit is set." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The teardown path is reached only through local interfaces — IOMMU domain attach/detach, SVA bind/unbind via accelerator char devices, and VFIO/iommufd ioctls — plus a locally-controlled device's DMA; there is no remote/network path to this code.\nAC:H - Triggering the torn read requires the IOMMU's internal multi-burst fetch of the 64-byte entry to interleave with the CPU's eight 64-bit zeroing writes during the narrow teardown window; this sub-microsecond hardware-internal timing is beyond the attacker's control and cannot be reliably reproduced.\nPR:L - Reaching the teardown requires local access to manage an IOMMU domain or to bind/unbind a PASID on an SVA-capable accelerator (reachable by an unprivileged user granted device access), not a pre-auth or fully unauthenticated path.\nUI:N - No victim interaction is needed; the attacker drives both the device DMA and the PASID-entry teardown.\nS:C - The IOMMU enforces the DMA isolation boundary; a torn/inconsistent PASID-entry read can cause the IOMMU to mistranslate a device's DMA, allowing access outside the device's authorized memory scope — an IOMMU/DMA boundary crossing.\nC:H - Mistranslation from an inconsistent entry read could let a device (e.g., guest-assigned or SVA-bound) read host physical memory outside its domain, yielding disclosure of memory beyond its authorized scope.\nI:H - The same mistranslation could let a device perform DMA writes to host physical memory outside its assigned domain, corrupting memory across the isolation boundary.\nA:H - The torn read causes \"spurious faults\" and \"unpredictable\" IOMMU behavior, which can produce DMA fault storms or device/translation failures impacting availability." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/iommu/intel/pasid.c", "drivers/iommu/intel/pasid.h" ], "versions": [ { "version": "0bbeb01a4fafbf8422e5c8882d461d6ac4f71e15", "lessThan": "a84d30e8d2bacd21782a6481158b7c9c552f4868", "status": "affected", "versionType": "git" }, { "version": "0bbeb01a4fafbf8422e5c8882d461d6ac4f71e15", "lessThan": "821807c167b7b48a41b95b6607c6b9f97600f7d9", "status": "affected", "versionType": "git" }, { "version": "0bbeb01a4fafbf8422e5c8882d461d6ac4f71e15", "lessThan": "949d71666e9dd19f21e7b4b53a88cd2c5b902858", "status": "affected", "versionType": "git" }, { "version": "0bbeb01a4fafbf8422e5c8882d461d6ac4f71e15", "lessThan": "75ed00055c059dedc47b5daaaa2f8a7a019138ff", "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/intel/pasid.c", "drivers/iommu/intel/pasid.h" ], "versions": [ { "version": "5.0", "status": "affected" }, { "version": "0", "lessThan": "5.0", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.75", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.14", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.4", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "5.0", "versionEndExcluding": "6.12.75" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.18.14" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.19.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a84d30e8d2bacd21782a6481158b7c9c552f4868" }, { "url": "https://git.kernel.org/stable/c/821807c167b7b48a41b95b6607c6b9f97600f7d9" }, { "url": "https://git.kernel.org/stable/c/949d71666e9dd19f21e7b4b53a88cd2c5b902858" }, { "url": "https://git.kernel.org/stable/c/75ed00055c059dedc47b5daaaa2f8a7a019138ff" } ], "title": "iommu/vt-d: Clear Present bit before tearing down PASID entry", "x_generator": { "engine": "bippy-1.2.0" } } } }