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CVE-2026-72172 (GCVE-0-2026-72172)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:53 – Updated: 2026-08-23 12:47
VLAI
Title
mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE If DAX memory is hotplugged into an unoccupied subsection of an early section, section_activate() reuses the unoptimized boot memmap. However, compound_nr_pages() still assumes that vmemmap optimization is in effect and initializes only the reduced number of struct pages. As a result, the remaining tail struct pages are left uninitialized, which can later lead to unexpected behavior or crashes. Fix this by treating early sections as unoptimized when calculating how many struct pages to initialize.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 6fd3620b342861de9547ea01d28f664892ef51a1 , < c5ef574d57e4a701485c13f26822328c91f05413 (git)
Affected: 6fd3620b342861de9547ea01d28f664892ef51a1 , < 511a60e71aec308b24722cffc1912bf6befb87bf (git)
Affected: 6fd3620b342861de9547ea01d28f664892ef51a1 , < 11f2826e9ee6f24aaa774e3dcd75abbe4b3091b6 (git)
Affected: 6fd3620b342861de9547ea01d28f664892ef51a1 , < da5234df0941665f3a3f5b80f3dab94046537be0 (git)
Affected: 6fd3620b342861de9547ea01d28f664892ef51a1 , < b91e27bce37cab9f35de0059278ebe457ca9878b (git)
Affected: 6fd3620b342861de9547ea01d28f664892ef51a1 , < cd681403a87085562499d60325b7b45d3be11217 (git)
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Linux Linux Affected: 5.19
Unaffected: 0 , < 5.19 (semver)
Unaffected: 6.1.184 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          "value": "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."
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              "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\u003e0) 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."
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    "datePublished": "2026-08-15T05:53:37.795Z",
    "dateReserved": "2026-08-09T03:40:39.910Z",
    "dateUpdated": "2026-08-23T12:47:00.343Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-18T15:19:58+00:00",
      "cve": "CVE-2026-72172",
      "id": "CVE-2026-72172",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "198",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72172.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.