{"api_version":"1","generated_at":"2026-08-22T04:27:12+00:00","cve":"CVE-2026-72172","urls":{"html":"https://cve.report/CVE-2026-72172","api":"https://cve.report/api/cve/CVE-2026-72172.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72172","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72172"},"summary":{"title":"mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/mm_init: fix uninitialized struct pages for ZONE_DEVICE\n\nIf DAX memory is hotplugged into an unoccupied subsection of an early\nsection, section_activate() reuses the unoptimized boot memmap.  However,\ncompound_nr_pages() still assumes that vmemmap optimization is in effect\nand initializes only the reduced number of struct pages.  As a result, the\nremaining tail struct pages are left uninitialized, which can later lead\nto unexpected behavior or crashes.\n\nFix this by treating early sections as unoptimized when calculating how\nmany struct pages to initialize.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:21:35","updated_at":"2026-08-17 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Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72172","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6fd3620b342861de9547ea01d28f664892ef51a1 511a60e71aec308b24722cffc1912bf6befb87bf git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6fd3620b342861de9547ea01d28f664892ef51a1 11f2826e9ee6f24aaa774e3dcd75abbe4b3091b6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6fd3620b342861de9547ea01d28f664892ef51a1 da5234df0941665f3a3f5b80f3dab94046537be0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6fd3620b342861de9547ea01d28f664892ef51a1 b91e27bce37cab9f35de0059278ebe457ca9878b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"72172","cve":"CVE-2026-72172","epss":"0.001630000","percentile":"0.060340000","score_date":"2026-08-17","updated_at":"2026-08-18 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the Linux kernel, the following vulnerability has been resolved:\n\nmm/mm_init: fix uninitialized struct pages for ZONE_DEVICE\n\nIf DAX memory is hotplugged into an unoccupied subsection of an early\nsection, section_activate() reuses the unoptimized boot memmap.  However,\ncompound_nr_pages() still assumes that vmemmap optimization is in effect\nand initializes only the reduced number of struct pages.  As a result, the\nremaining tail struct pages are left uninitialized, which can later lead\nto unexpected behavior or crashes.\n\nFix this by treating early sections as unoptimized when calculating how\nmany struct pages to initialize."}],"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 flaw is in memmap_init_zone_device() reached via memremap_pages()/devm_memremap_pages() during device-DAX driver probe or ZONE_DEVICE hotplug (e.g., dev_dax_probe, Hyper-V VTL), not via network protocols; subsequent impact is triggered by local mmap/page-fault/get_user_pages activity on the DAX device.\nAC:L - After device-DAX with compound vmemmap (vmemmap_shift>0) is hotplugged into an unoccupied early-section subsection, uninitialized tail struct pages remain indefinitely; an attacker only needs to access that memory (e.g., mmap /dev/dax) to invoke kernel page-metadata operations, without races or uncontrollable victim state.\nPR:L - While initial ZONE_DEVICE hotplug requires administrator device-DAX configuration (daxctl/ndctl, driver bind), on a configured persistent-memory or cloud server unprivileged local users with /dev/dax access can trigger kernel use of the corrupt struct pages via mmap and page faults without CAP_SYS_ADMIN in the init namespace.\nUI:N - Exploitation requires no victim interaction beyond the attacker (or any local user) running programs that mmap or access the already-provisioned DAX device; no mount, click, or plug/unplug action by another user is needed at exploit time.\nS:U - Impact is kernel memory corruption, information disclosure, and denial of service within the host kernel security boundary; it does not inherently cross VM/host, IOMMU, or sandbox isolation even though cloud persistent-memory deployments are a plausible high-impact scenario.\nC:H - Uninitialized tail struct page metadata (flags, refcount, pgmap/lru fields) is later interpreted as valid by the MM subsystem; garbage contents can be read through page-table walks, refcount checks, and folio lookups, yielding kernel memory disclosure comparable to other uninitialized-page corruption bugs.\nI:H - Corrupt struct page fields can drive incorrect refcounting, compound-head/tail linkage, and ZONE_DEVICE pgmap handling, enabling heap-style memory corruption and potential arbitrary kernel write or control-flow hijack, not merely bounded data modification.\nA:H - The fix commit and call path explicitly warn of unexpected behavior and crashes; operations on uninitialized struct pages can provoke kernel oops, BUG_ON, use-after-free, or panic during page allocation, migration, or DAX fault handling, giving reliable denial of service."}]}],"providerMetadata":{"dateUpdated":"2026-08-17T05:41:10.423Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/511a60e71aec308b24722cffc1912bf6befb87bf"},{"url":"https://git.kernel.org/stable/c/11f2826e9ee6f24aaa774e3dcd75abbe4b3091b6"},{"url":"https://git.kernel.org/stable/c/da5234df0941665f3a3f5b80f3dab94046537be0"},{"url":"https://git.kernel.org/stable/c/b91e27bce37cab9f35de0059278ebe457ca9878b"},{"url":"https://git.kernel.org/stable/c/cd681403a87085562499d60325b7b45d3be11217"}],"title":"mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72172","datePublished":"2026-08-15T05:53:37.795Z","dateReserved":"2026-08-09T03:40:39.910Z","dateUpdated":"2026-08-17T05:41:10.423Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:21:35","lastModifiedDate":"2026-08-17 06:18:17","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":"72172","Ordinal":"1","Title":"mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE","CVE":"CVE-2026-72172","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72172","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/mm_init: fix uninitialized struct pages for ZONE_DEVICE\n\nIf DAX memory is hotplugged into an unoccupied subsection of an early\nsection, section_activate() reuses the unoptimized boot memmap.  However,\ncompound_nr_pages() still assumes that vmemmap optimization is in effect\nand initializes only the reduced number of struct pages.  As a result, the\nremaining tail struct pages are left uninitialized, which can later lead\nto unexpected behavior or crashes.\n\nFix this by treating early sections as unoptimized when calculating how\nmany struct pages to initialize.","Type":"Description","Title":"mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE"}]}}}