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CVE-2026-89574 (GCVE-0-2026-89574)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:44 – Updated: 2026-09-13 06:31
VLAI
Title
dm array: validate array block headers on read
Summary
In the Linux kernel, the following vulnerability has been resolved: dm array: validate array block headers on read array_block_check() validates blocknr and csum and nothing else, while node_check(), next to it, has bounded the structural fields since both were written. dm_array_cursor_next() takes its loop bound from the on-disk nr_entries and element_at() is unguarded pointer arithmetic, so a count larger than the block holds keeps the cursor in one block while the index grows past it and the read walks off the dm-bufio buffer -- dm_cache_load_mappings() drives it once per cache block at activation. Check the header against itself: reject a zero value_size, require max_entries to equal calc_max_entries() for that value_size and block size, and require nr_entries to fit. Equality rather than an upper bound, since a count below the real capacity trips BUG_ON() in fill_ablock() and trim_ablock(). Metadata dm-array writes satisfies all three.
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: 6513c29f44f2cc970c0e9fecfe5a6526c3e73025 , < 67adda7ed5da3e3b64f5b9021a02c21fb374fd9c (git)
Affected: 6513c29f44f2cc970c0e9fecfe5a6526c3e73025 , < b33f76d33aaeacf3baf3370d8d64985169b36600 (git)
Affected: 6513c29f44f2cc970c0e9fecfe5a6526c3e73025 , < 9808ddffb4bc659352df3020cd84d9d864820ee5 (git)
Affected: 6513c29f44f2cc970c0e9fecfe5a6526c3e73025 , < 2965787723084835b18dfe993cd450ebf5bd4540 (git)
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Linux Linux Affected: 3.9
Unaffected: 0 , < 3.9 (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/persistent-data/dm-array.c"
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            "version": "3.1"
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              "value": "AV:L - The bug is reached when the kernel reads attacker-crafted dm-array metadata from a local block device during device-mapper activation (dm-cache dm_cache_load_mappings, dm-clone bitset load, or dm-era array resize), not via a network protocol.\nAC:L - The attacker fully controls the on-disk array-block header (nr_entries, max_entries, value_size) and can compute a matching checksum, so activation deterministically walks off the dm-bufio buffer; there is no race or attacker-uncontrollable memory layout.\nPR:L - Device-mapper ioctls require init-namespace CAP_SYS_ADMIN and are not reachable via user namespaces, but the malformed data is on-disk metadata, so the attacker only needs write access to the backing store (loop file, VM/container disk, iSCSI/NBD LUN) that a dm-cache/dm-era/dm-clone stack is built on.\nUI:N - Once corrupt metadata is on the backing store, LVM/udev autoactivation, boot, or reattachment of the volume loads mappings without a separate victim action such as mounting a filesystem or opening a file.\nS:U - The out-of-bounds access is confined to kernel dm-bufio metadata buffers on the same host; this is ordinary kernel memory corruption, not a VM escape, IOMMU bypass, or sandbox boundary crossing.\nC:H - dm_array_cursor_next() takes its loop bound from on-disk nr_entries while element_at() is unguarded pointer arithmetic, so a too-large count keeps the cursor in one block and reads past the dm-bufio data buffer (typically a 4K slab/page) for every cache block at activation, an unbounded kernel out-of-bounds read.\nI:H - Unchecked headers let fill_ablock()/trim_ablock() hit BUG_ON on resize, and out-of-bounds mapping, hint, and bitset values from adjacent kernel memory are installed into the cache policy and then used for origin/cache I/O, giving a memory-corruption integrity primitive.\nA:H - Walking off the dm-bufio buffer causes a kernel oops or KASAN panic, and an undersized on-disk max_entries hits BUG_ON in fill_ablock() and trim_ablock() during array resize at activation."
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/2965787723084835b18dfe993cd450ebf5bd4540"
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    "cveId": "CVE-2026-89574",
    "datePublished": "2026-09-11T19:44:42.494Z",
    "dateReserved": "2026-09-11T19:38:34.727Z",
    "dateUpdated": "2026-09-13T06:31:11.485Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-13T06:58:11+00:00",
      "cve": "CVE-2026-89574",
      "id": "CVE-2026-89574",
      "initial_release_date": "2026-09-11T19:44:42.494000+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel: dm array out-of-bounds read due to insufficient header validation",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89574.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T00:58:21Z",
      "cve": "CVE-2026-89574",
      "id": "CVE-2026-89574",
      "initial_release_date": "2026-09-15T00:58:21Z",
      "product_status:known_affected": "349",
      "product_status:known_not_affected": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89574",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89574.json",
      "version": "2"
    }
  }
}



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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

Author Source Type Date Other

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.