{"api_version":"1","generated_at":"2026-08-15T08:46:50+00:00","cve":"CVE-2026-74439","urls":{"html":"https://cve.report/CVE-2026-74439","api":"https://cve.report/api/cve/CVE-2026-74439.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74439","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74439"},"summary":{"title":"iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry","description":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Clear Present bit before tearing down scalable-mode context entry\n\ndevice_pasid_table_teardown() zeroes the 128-bit scalable-mode context\nentry with context_clear_entry() while the Present bit is still set. This\ncreates a window where the hardware can fetch a torn entry, with some\nfields already zeroed while Present is still set, leading to unpredictable\nbehavior or spurious faults. The context-cache invalidation is issued only\nafter the entry has been zeroed, and intel_pasid_free_table() then frees\nthe PASID directory pages, so the IOMMU can keep walking a stale Present=1\nentry that points at freed memory.\n\nWhile x86 provides strong write ordering, the compiler may reorder the two\n64-bit writes to the entry, and the hardware fetch is not guaranteed to be\natomic with respect to multiple CPU writes.\n\nCommit c1e4f1dccbe9d (\"iommu/vt-d: Clear Present bit before tearing down\ncontext entry\") fixed this exact pattern in domain_context_clear_one() and\nthe copied-context path, but device_pasid_table_teardown() was not\nconverted.\n\nAlign it with the \"Guidance to Software for Invalidations\" in the VT-d\nspec, Section 6.5.3.3, using the same ownership handshake as the sibling\nfix: clear only the Present bit, flush it to the IOMMU, perform the\ncontext-cache invalidation, and only then zero the rest of the entry.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:22:46","updated_at":"2026-08-15 06:22:46"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/e9e83bcfe37dc719182500dd823c03ab57d934f0","name":"https://git.kernel.org/stable/c/e9e83bcfe37dc719182500dd823c03ab57d934f0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7fd4077dc92b91b1b844333c0a06bb9e286db10a","name":"https://git.kernel.org/stable/c/7fd4077dc92b91b1b844333c0a06bb9e286db10a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/588718101e8449605f1c7e858fecb7cfa701cdab","name":"https://git.kernel.org/stable/c/588718101e8449605f1c7e858fecb7cfa701cdab","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f46452c3df7a8d8a5addc0926e76ef19ea7da0a0","name":"https://git.kernel.org/stable/c/f46452c3df7a8d8a5addc0926e76ef19ea7da0a0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74439","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74439","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 81e921fd321614c2ad8ac333b041aae1da7a1c6d e9e83bcfe37dc719182500dd823c03ab57d934f0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 81e921fd321614c2ad8ac333b041aae1da7a1c6d 588718101e8449605f1c7e858fecb7cfa701cdab git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 81e921fd321614c2ad8ac333b041aae1da7a1c6d 7fd4077dc92b91b1b844333c0a06bb9e286db10a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 81e921fd321614c2ad8ac333b041aae1da7a1c6d f46452c3df7a8d8a5addc0926e76ef19ea7da0a0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 333fe86968482ca701c609af590003bcea450e8f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.8.2 6.9 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.9","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.9 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.97 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.40 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.5 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/iommu/intel/pasid.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"e9e83bcfe37dc719182500dd823c03ab57d934f0","status":"affected","version":"81e921fd321614c2ad8ac333b041aae1da7a1c6d","versionType":"git"},{"lessThan":"588718101e8449605f1c7e858fecb7cfa701cdab","status":"affected","version":"81e921fd321614c2ad8ac333b041aae1da7a1c6d","versionType":"git"},{"lessThan":"7fd4077dc92b91b1b844333c0a06bb9e286db10a","status":"affected","version":"81e921fd321614c2ad8ac333b041aae1da7a1c6d","versionType":"git"},{"lessThan":"f46452c3df7a8d8a5addc0926e76ef19ea7da0a0","status":"affected","version":"81e921fd321614c2ad8ac333b041aae1da7a1c6d","versionType":"git"},{"status":"affected","version":"333fe86968482ca701c609af590003bcea450e8f","versionType":"git"},{"lessThan":"6.9","status":"affected","version":"6.8.2","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/iommu/intel/pasid.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.9"},{"lessThan":"6.9","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.97","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.40","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.97","versionStartIncluding":"6.9","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.40","versionStartIncluding":"6.9","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.5","versionStartIncluding":"6.9","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc1","versionStartIncluding":"6.9","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8.2","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Clear Present bit before tearing down scalable-mode context entry\n\ndevice_pasid_table_teardown() zeroes the 128-bit scalable-mode context\nentry with context_clear_entry() while the Present bit is still set. This\ncreates a window where the hardware can fetch a torn entry, with some\nfields already zeroed while Present is still set, leading to unpredictable\nbehavior or spurious faults. The context-cache invalidation is issued only\nafter the entry has been zeroed, and intel_pasid_free_table() then frees\nthe PASID directory pages, so the IOMMU can keep walking a stale Present=1\nentry that points at freed memory.\n\nWhile x86 provides strong write ordering, the compiler may reorder the two\n64-bit writes to the entry, and the hardware fetch is not guaranteed to be\natomic with respect to multiple CPU writes.\n\nCommit c1e4f1dccbe9d (\"iommu/vt-d: Clear Present bit before tearing down\ncontext entry\") fixed this exact pattern in domain_context_clear_one() and\nthe copied-context path, but device_pasid_table_teardown() was not\nconverted.\n\nAlign it with the \"Guidance to Software for Invalidations\" in the VT-d\nspec, Section 6.5.3.3, using the same ownership handshake as the sibling\nfix: clear only the Present bit, flush it to the IOMMU, perform the\ncontext-cache invalidation, and only then zero the rest of the entry."}],"providerMetadata":{"dateUpdated":"2026-08-15T05:59:36.655Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/e9e83bcfe37dc719182500dd823c03ab57d934f0"},{"url":"https://git.kernel.org/stable/c/588718101e8449605f1c7e858fecb7cfa701cdab"},{"url":"https://git.kernel.org/stable/c/7fd4077dc92b91b1b844333c0a06bb9e286db10a"},{"url":"https://git.kernel.org/stable/c/f46452c3df7a8d8a5addc0926e76ef19ea7da0a0"}],"title":"iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74439","datePublished":"2026-08-15T05:59:36.655Z","dateReserved":"2026-08-15T05:44:03.897Z","dateUpdated":"2026-08-15T05:59:36.655Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:22:46","lastModifiedDate":"2026-08-15 06:22:46","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74439","Ordinal":"1","Title":"iommu/vt-d: Clear Present bit before tearing down scalable-mode ","CVE":"CVE-2026-74439","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74439","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Clear Present bit before tearing down scalable-mode context entry\n\ndevice_pasid_table_teardown() zeroes the 128-bit scalable-mode context\nentry with context_clear_entry() while the Present bit is still set. This\ncreates a window where the hardware can fetch a torn entry, with some\nfields already zeroed while Present is still set, leading to unpredictable\nbehavior or spurious faults. The context-cache invalidation is issued only\nafter the entry has been zeroed, and intel_pasid_free_table() then frees\nthe PASID directory pages, so the IOMMU can keep walking a stale Present=1\nentry that points at freed memory.\n\nWhile x86 provides strong write ordering, the compiler may reorder the two\n64-bit writes to the entry, and the hardware fetch is not guaranteed to be\natomic with respect to multiple CPU writes.\n\nCommit c1e4f1dccbe9d (\"iommu/vt-d: Clear Present bit before tearing down\ncontext entry\") fixed this exact pattern in domain_context_clear_one() and\nthe copied-context path, but device_pasid_table_teardown() was not\nconverted.\n\nAlign it with the \"Guidance to Software for Invalidations\" in the VT-d\nspec, Section 6.5.3.3, using the same ownership handshake as the sibling\nfix: clear only the Present bit, flush it to the IOMMU, perform the\ncontext-cache invalidation, and only then zero the rest of the entry.","Type":"Description","Title":"iommu/vt-d: Clear Present bit before tearing down scalable-mode "}]}}}