{"api_version":"1","generated_at":"2026-08-22T17:47:26+00:00","cve":"CVE-2026-68163","urls":{"html":"https://cve.report/CVE-2026-68163","api":"https://cve.report/api/cve/CVE-2026-68163.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-68163","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-68163"},"summary":{"title":"mm/page_vma_mapped: fix device-private PMD handling","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/page_vma_mapped: fix device-private PMD handling\n\nCommit 65edfda6f3f2 (\"mm/rmap: extend rmap and migration support\ndevice-private entries\") introduced the concept of device-private PMD\nentries, but did not correctly update the rmap walk code to account for\nthem.\n\nAs a result, when page_vma_mapped_walk() encounters device-private PMD\nentries, it takes no action other than to acquire the PMD lock and exit.\n\nHowever this is highly problematic for two reasons - firstly, device\nprivate entries possess a PFN so check_pmd() needs to be called to ensure\nan overlapping PFN range.\n\nSecondly, and more importantly, if PVMW_MIGRATION is set the caller\nassumes the returned entry is a migration entry, resulting in memory\ncorruption when the caller tries to interpret the device private entry as\nsuch.\n\nIn addition, commit 146287290023 (\"mm/huge_memory: implement\ndevice-private THP splitting\") allowed device private PMDs to be split\nlike THP mappings, but again did not update this code path.\n\nAs a result, we might race a PMD split prior to acquiring the PMD lock.\n\nThis patch addresses all of these issues by invoking check_pmd(), ensuring\nPMVW_MIGRATION is not set and checks whether a split raced us we do for\nPMD THP and migration entries.\n\nInstead of checking for a subset of the cases after taking the pmd_lock(),\nput device-private along with pmd_trans_huge() and\npmd_is_migration_entry().  Also remove thp_migration_supported() as it is\nalready guarded by pmd_is_migration_entry().\n\n[akpm@linux-foundation.org: fix Raspberry Pi 1 build, per David]","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-10 13:20:02","updated_at":"2026-08-17 05:18:16"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/f84ca9b1888d8fce7dfefe0e750fa971f8797486","name":"https://git.kernel.org/stable/c/f84ca9b1888d8fce7dfefe0e750fa971f8797486","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ab6209f4b48a98ef14d6766acdb62aa9bb32e670","name":"https://git.kernel.org/stable/c/ab6209f4b48a98ef14d6766acdb62aa9bb32e670","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-68163","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68163","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 65edfda6f3f2e58f757485a056e4f1775a1404a8 ab6209f4b48a98ef14d6766acdb62aa9bb32e670 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 65edfda6f3f2e58f757485a056e4f1775a1404a8 f84ca9b1888d8fce7dfefe0e750fa971f8797486 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.19","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.6 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"68163","cve":"CVE-2026-68163","epss":"0.001650000","percentile":"0.062000000","score_date":"2026-08-17","updated_at":"2026-08-18 00:11:47"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["mm/page_vma_mapped.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"ab6209f4b48a98ef14d6766acdb62aa9bb32e670","status":"affected","version":"65edfda6f3f2e58f757485a056e4f1775a1404a8","versionType":"git"},{"lessThan":"f84ca9b1888d8fce7dfefe0e750fa971f8797486","status":"affected","version":"65edfda6f3f2e58f757485a056e4f1775a1404a8","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["mm/page_vma_mapped.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.19"},{"lessThan":"6.19","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.6","versionStartIncluding":"6.19","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"6.19","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/page_vma_mapped: fix device-private PMD handling\n\nCommit 65edfda6f3f2 (\"mm/rmap: extend rmap and migration support\ndevice-private entries\") introduced the concept of device-private PMD\nentries, but did not correctly update the rmap walk code to account for\nthem.\n\nAs a result, when page_vma_mapped_walk() encounters device-private PMD\nentries, it takes no action other than to acquire the PMD lock and exit.\n\nHowever this is highly problematic for two reasons - firstly, device\nprivate entries possess a PFN so check_pmd() needs to be called to ensure\nan overlapping PFN range.\n\nSecondly, and more importantly, if PVMW_MIGRATION is set the caller\nassumes the returned entry is a migration entry, resulting in memory\ncorruption when the caller tries to interpret the device private entry as\nsuch.\n\nIn addition, commit 146287290023 (\"mm/huge_memory: implement\ndevice-private THP splitting\") allowed device private PMDs to be split\nlike THP mappings, but again did not update this code path.\n\nAs a result, we might race a PMD split prior to acquiring the PMD lock.\n\nThis patch addresses all of these issues by invoking check_pmd(), ensuring\nPMVW_MIGRATION is not set and checks whether a split raced us we do for\nPMD THP and migration entries.\n\nInstead of checking for a subset of the cases after taking the pmd_lock(),\nput device-private along with pmd_trans_huge() and\npmd_is_migration_entry().  Also remove thp_migration_supported() as it is\nalready guarded by pmd_is_migration_entry().\n\n[akpm@linux-foundation.org: fix Raspberry Pi 1 build, per David]"}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The bug is in the MM rmap/page-table walk reached only from in-kernel memory-management paths (migrate_vma finalize, rmap unmap/migration) triggered by local syscalls and GPU driver ioctls (AMD KFD, nouveau, drm_pagemap), not from network packet handling.\nAC:L - An attacker with GPU/HMM access can reliably create device-private THP PMDs and drive migrate_vma/setup/finalize while racing PMD splits via concurrent threads; both sides of the race are attacker-controlled, not dependent on admin timing or uncontrollable layout.\nPR:L - Exploitation needs only an unprivileged local user who can use the GPU/HMM stack (typical render/video group access on ML/cloud GPU nodes) to allocate device-private THP and invoke migration; it does not require real root in the init namespace.\nUI:N - No victim interaction is required; memory migration and PMD splitting are driven entirely by the attacker's own process through normal GPU unified-memory/migration APIs and concurrent threads.\nS:U - Impact is kernel page-table corruption and local privilege escalation within the host kernel security domain; it is not a VM guest-to-host escape, IOMMU bypass, or cross-authority sandbox breakout per kernel CVSS scope guidance.\nC:H - Misinterpreting a device-private PMD as a migration entry corrupts page tables and rmap state; such MM corruption is readily weaponizable for arbitrary kernel memory reads, not merely a bounded leak.\nI:H - The faulty walk causes remove_migration_pmd() and related callers to install incorrect PMD/PTE contents from mis-typed entries, enabling arbitrary kernel memory writes and control-flow hijack via page-table manipulation.\nA:H - Incorrect PMD handling during migration or concurrent THP splitting can cause kernel oops/panic, use-after-free conditions, or hung migration paths, producing full system denial of service even before successful exploitation."}]}],"providerMetadata":{"dateUpdated":"2026-08-17T05:00:02.619Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/ab6209f4b48a98ef14d6766acdb62aa9bb32e670"},{"url":"https://git.kernel.org/stable/c/f84ca9b1888d8fce7dfefe0e750fa971f8797486"}],"title":"mm/page_vma_mapped: fix device-private PMD handling","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-68163","datePublished":"2026-08-10T11:59:30.633Z","dateReserved":"2026-07-30T09:28:09.372Z","dateUpdated":"2026-08-17T05:00:02.619Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-10 13:20:02","lastModifiedDate":"2026-08-17 05:18:16","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"68163","Ordinal":"1","Title":"mm/page_vma_mapped: fix device-private PMD handling","CVE":"CVE-2026-68163","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"68163","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/page_vma_mapped: fix device-private PMD handling\n\nCommit 65edfda6f3f2 (\"mm/rmap: extend rmap and migration support\ndevice-private entries\") introduced the concept of device-private PMD\nentries, but did not correctly update the rmap walk code to account for\nthem.\n\nAs a result, when page_vma_mapped_walk() encounters device-private PMD\nentries, it takes no action other than to acquire the PMD lock and exit.\n\nHowever this is highly problematic for two reasons - firstly, device\nprivate entries possess a PFN so check_pmd() needs to be called to ensure\nan overlapping PFN range.\n\nSecondly, and more importantly, if PVMW_MIGRATION is set the caller\nassumes the returned entry is a migration entry, resulting in memory\ncorruption when the caller tries to interpret the device private entry as\nsuch.\n\nIn addition, commit 146287290023 (\"mm/huge_memory: implement\ndevice-private THP splitting\") allowed device private PMDs to be split\nlike THP mappings, but again did not update this code path.\n\nAs a result, we might race a PMD split prior to acquiring the PMD lock.\n\nThis patch addresses all of these issues by invoking check_pmd(), ensuring\nPMVW_MIGRATION is not set and checks whether a split raced us we do for\nPMD THP and migration entries.\n\nInstead of checking for a subset of the cases after taking the pmd_lock(),\nput device-private along with pmd_trans_huge() and\npmd_is_migration_entry().  Also remove thp_migration_supported() as it is\nalready guarded by pmd_is_migration_entry().\n\n[akpm@linux-foundation.org: fix Raspberry Pi 1 build, per David]","Type":"Description","Title":"mm/page_vma_mapped: fix device-private PMD handling"}]}}}