{"id":"CVE-2026-45945","state":"PUBLISHED","title":"iommu/vt-d: Fix race condition during PASID entry replacement","description":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Fix race condition during PASID entry replacement\n\nThe Intel VT-d PASID table entry is 512 bits (64 bytes). When replacing\nan active PASID entry (e.g., during domain replacement), the current\nimplementation calculates a new entry on the stack and copies it to the\ntable using a single structure assignment.\n\n        struct pasid_entry *pte, new_pte;\n\n        pte = intel_pasid_get_entry(dev, pasid);\n        pasid_pte_config_first_level(iommu, &new_pte, ...);\n        *pte = new_pte;\n\nBecause the hardware may fetch the 512-bit PASID entry in multiple\n128-bit chunks, updating the entire entry while it is active (Present\nbit set) risks a \"torn\" read. In this scenario, the IOMMU hardware\ncould observe an inconsistent state — partially new data and partially\nold data — leading to unpredictable behavior or spurious faults.\n\nFix this by removing the unsafe \"replace\" helpers and following the\n\"clear-then-update\" flow, which ensures the Present bit is cleared and\nthe required invalidation handshake is completed before the new\nconfiguration is applied.","publishedAt":"2026-05-27T12:18:01.345Z","updatedAt":"2026-10-19T19:26:40.294Z","severity":{"score":8.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7543ee63e8113aa34b07df3b16b3b9d2c5f73939","status":"affected","lessThan":"4718007870547e1efebbdd6745d9fce58f008fef","versionType":"git"},{"version":"7543ee63e8113aa34b07df3b16b3b9d2c5f73939","status":"affected","lessThan":"66a7aff480a82b8642b3991fed5fdc9780022157","versionType":"git"},{"version":"7543ee63e8113aa34b07df3b16b3b9d2c5f73939","status":"affected","lessThan":"c3b1edea3791fa91ab7032faa90355913ad9451b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/intel/iommu.c","drivers/iommu/intel/nested.c","drivers/iommu/intel/pasid.c","drivers/iommu/intel/pasid.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.13","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.4","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/intel/iommu.c","drivers/iommu/intel/nested.c","drivers/iommu/intel/pasid.c","drivers/iommu/intel/pasid.h"]}],"references":["https://git.kernel.org/stable/c/4718007870547e1efebbdd6745d9fce58f008fef","https://git.kernel.org/stable/c/66a7aff480a82b8642b3991fed5fdc9780022157","https://git.kernel.org/stable/c/c3b1edea3791fa91ab7032faa90355913ad9451b"],"weaknesses":["CWE-362"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/45xxx/CVE-2026-45945.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-45945","state":"PUBLISHED","datePublished":"2026-05-27T12:18:01.345Z","dateUpdated":"2026-10-19T19:26:40.294Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-13T15:03:33.088Z"},"containers":{"cna":{"title":"iommu/vt-d: Fix race condition during PASID entry replacement","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Fix race condition during PASID entry replacement\n\nThe Intel VT-d PASID table entry is 512 bits (64 bytes). When replacing\nan active PASID entry (e.g., during domain replacement), the current\nimplementation calculates a new entry on the stack and copies it to the\ntable using a single structure assignment.\n\n        struct pasid_entry *pte, new_pte;\n\n        pte = intel_pasid_get_entry(dev, pasid);\n        pasid_pte_config_first_level(iommu, &new_pte, ...);\n        *pte = new_pte;\n\nBecause the hardware may fetch the 512-bit PASID entry in multiple\n128-bit chunks, updating the entire entry while it is active (Present\nbit set) risks a \"torn\" read. In this scenario, the IOMMU hardware\ncould observe an inconsistent state — partially new data and partially\nold data — leading to unpredictable behavior or spurious faults.\n\nFix this by removing the unsafe \"replace\" helpers and following the\n\"clear-then-update\" flow, which ensures the Present bit is cleared and\nthe required invalidation handshake is completed before the new\nconfiguration is applied."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7543ee63e8113aa34b07df3b16b3b9d2c5f73939","status":"affected","lessThan":"4718007870547e1efebbdd6745d9fce58f008fef","versionType":"git"},{"version":"7543ee63e8113aa34b07df3b16b3b9d2c5f73939","status":"affected","lessThan":"66a7aff480a82b8642b3991fed5fdc9780022157","versionType":"git"},{"version":"7543ee63e8113aa34b07df3b16b3b9d2c5f73939","status":"affected","lessThan":"c3b1edea3791fa91ab7032faa90355913ad9451b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/intel/iommu.c","drivers/iommu/intel/nested.c","drivers/iommu/intel/pasid.c","drivers/iommu/intel/pasid.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.13","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.4","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/intel/iommu.c","drivers/iommu/intel/nested.c","drivers/iommu/intel/pasid.c","drivers/iommu/intel/pasid.h"]}],"references":[{"url":"https://git.kernel.org/stable/c/4718007870547e1efebbdd6745d9fce58f008fef"},{"url":"https://git.kernel.org/stable/c/66a7aff480a82b8642b3991fed5fdc9780022157"},{"url":"https://git.kernel.org/stable/c/c3b1edea3791fa91ab7032faa90355913ad9451b"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable replace path is reached only through local IOMMUFD/VFIO ioctls (`/dev/iommu` device PASID domain replacement); there is no network or remote-peer path to this code.\nAC:L - Although it is a hardware/software race on the 128-bit-chunked entry fetch, the attacker controls both sides — driving continuous device DMA (forcing frequent entry fetches) while repeatedly issuing the replacement ioctl — so the torn-entry window is reliably reachable through repetition.\nPR:L - Triggering domain replacement requires IOMMUFD/VFIO access to an assigned device, which is gated by device-file permissions rather than an init-namespace root capability check; a confined VMM/user granted passthrough suffices.\nUI:N - The replacement and concurrent DMA are entirely attacker-driven; no action by another user is needed.\nS:C - The flaw is in the IOMMU DMA-isolation structure, and a torn PASID entry can let a device's DMA escape its assigned domain — an IOMMU/DMA boundary bypass that crosses the security authority of the affected component.\nC:H - A torn page-table-pointer field can cause the IOMMU to translate device DMA through stale/corrupt tables, allowing the device to read host or other-domain physical memory across the isolation boundary.\nI:H - The same mistranslation gives the device a write primitive into memory outside its domain, enabling corruption of host/other-domain memory.\nA:H - The commit explicitly notes the torn entry causes \"unpredictable behavior or spurious faults,\" which can manifest as IOMMU faults, device failures, or kernel crashes."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:28:52.094Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.19.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-45945","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:18:33.300582Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-362","lang":"en","type":"CWE","description":"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:26:40.294Z"}}]}}}