{"id":"CVE-2026-74439","revision":"ce6a36d53dae492b8b0837d3a630dcdf","records":[{"revision":"ce6a36d53dae492b8b0837d3a630dcdf","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-74439","aliases":[],"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":0,"publishedAt":"2026-08-15T05:59:36.655+00:00","modifiedAt":"2026-10-16T19:05:45.325+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/iommu/intel/pasid.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"81e921fd321614c2ad8ac333b041aae1da7a1c6d\",\n                            \"lessThan\": \"e9e83bcfe37dc719182500dd823c03ab57d934f0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"81e921fd321614c2ad8ac333b041aae1da7a1c6d\",\n                            \"lessThan\": \"588718101e8449605f1c7e858fecb7cfa701cdab\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"81e921fd321614c2ad8ac333b041aae1da7a1c6d\",\n                            \"lessThan\": \"7fd4077dc92b91b1b844333c0a06bb9e286db10a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"81e921fd321614c2ad8ac333b041aae1da7a1c6d\",\n                            \"lessThan\": \"f46452c3df7a8d8a5addc0926e76ef19ea7da0a0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"333fe86968482ca701c609af590003bcea450e8f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"6.8.2\",\n                            \"lessThan\": \"6.9\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/iommu/intel/pasid.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.9\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.9\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.97\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.40\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1.5\",\n                            \"lessThanOrEqual\": \"7.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","score":9.3,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/e9e83bcfe37dc719182500dd823c03ab57d934f0","https://git.kernel.org/stable/c/588718101e8449605f1c7e858fecb7cfa701cdab","https://git.kernel.org/stable/c/7fd4077dc92b91b1b844333c0a06bb9e286db10a","https://git.kernel.org/stable/c/f46452c3df7a8d8a5addc0926e76ef19ea7da0a0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74439","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-74439","identifiers":["CVE-2026-74439"]},"retained":false,"historicalAffected":[]}],"coverage":[]}