{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-68163", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-30T09:28:09.372Z", "datePublished": "2026-08-10T11:59:30.633Z", "dateUpdated": "2026-08-17T05:00:02.619Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:00:02.619Z" }, "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": { "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" }, "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "mm/page_vma_mapped.c" ], "versions": [ { "version": "65edfda6f3f2e58f757485a056e4f1775a1404a8", "lessThan": "ab6209f4b48a98ef14d6766acdb62aa9bb32e670", "status": "affected", "versionType": "git" }, { "version": "65edfda6f3f2e58f757485a056e4f1775a1404a8", "lessThan": "f84ca9b1888d8fce7dfefe0e750fa971f8797486", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "mm/page_vma_mapped.c" ], "versions": [ { "version": "6.19", "status": "affected" }, { "version": "0", "lessThan": "6.19", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.6", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "6.19", "versionEndExcluding": "7.1.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.2" } ] } ] } ], "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" } } } }