CVE-2026-23230 (GCVE-0-2026-23230)

Vulnerability from cvelistv5 – Published: 2026-02-18 14:53 – Updated: 2026-02-18 14:53
VLAI?
Title
smb: client: split cached_fid bitfields to avoid shared-byte RMW races
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: split cached_fid bitfields to avoid shared-byte RMW races is_open, has_lease and on_list are stored in the same bitfield byte in struct cached_fid but are updated in different code paths that may run concurrently. Bitfield assignments generate byte read–modify–write operations (e.g. `orb $mask, addr` on x86_64), so updating one flag can restore stale values of the others. A possible interleaving is: CPU1: load old byte (has_lease=1, on_list=1) CPU2: clear both flags (store 0) CPU1: RMW store (old | IS_OPEN) -> reintroduces cleared bits To avoid this class of races, convert these flags to separate bool fields.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 4386f6af8aaedd0c5ad6f659b40cadcc8f423828 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 3eaa22d688311c708b73f3c68bc6d0c8e3f0f77a (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < c4b9edd55987384a1f201d3d07ff71e448d79c1b (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 4cfa4c37dcbcfd70866e856200ed8a2894cac578 (git)
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    Linux Linux Unaffected: 6.6.125 , ≤ 6.6.* (semver)
Unaffected: 6.12.72 , ≤ 6.12.* (semver)
Unaffected: 6.18.11 , ≤ 6.18.* (semver)
Unaffected: 6.19.1 , ≤ 6.19.* (semver)
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{
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          "programFiles": [
            "fs/smb/client/cached_dir.h"
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          "vendor": "Linux",
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              "versionType": "semver"
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              "version": "6.12.72",
              "versionType": "semver"
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: split cached_fid bitfields to avoid shared-byte RMW races\n\nis_open, has_lease and on_list are stored in the same bitfield byte in\nstruct cached_fid but are updated in different code paths that may run\nconcurrently. Bitfield assignments generate byte read\u2013modify\u2013write\noperations (e.g. `orb $mask, addr` on x86_64), so updating one flag can\nrestore stale values of the others.\n\nA possible interleaving is:\n    CPU1: load old byte (has_lease=1, on_list=1)\n    CPU2: clear both flags (store 0)\n    CPU1: RMW store (old | IS_OPEN) -\u003e reintroduces cleared bits\n\nTo avoid this class of races, convert these flags to separate bool\nfields."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-02-18T14:53:34.078Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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      ],
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23230",
    "datePublished": "2026-02-18T14:53:34.078Z",
    "dateReserved": "2026-01-13T15:37:45.988Z",
    "dateUpdated": "2026-02-18T14:53:34.078Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23230\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-02-18T16:22:32.807\",\"lastModified\":\"2026-02-18T17:51:53.510\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nsmb: client: split cached_fid bitfields to avoid shared-byte RMW races\\n\\nis_open, has_lease and on_list are stored in the same bitfield byte in\\nstruct cached_fid but are updated in different code paths that may run\\nconcurrently. Bitfield assignments generate byte read\u2013modify\u2013write\\noperations (e.g. `orb $mask, addr` on x86_64), so updating one flag can\\nrestore stale values of the others.\\n\\nA possible interleaving is:\\n    CPU1: load old byte (has_lease=1, on_list=1)\\n    CPU2: clear both flags (store 0)\\n    CPU1: RMW store (old | IS_OPEN) -\u003e reintroduces cleared bits\\n\\nTo avoid this class of races, convert these flags to separate bool\\nfields.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/3eaa22d688311c708b73f3c68bc6d0c8e3f0f77a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/4386f6af8aaedd0c5ad6f659b40cadcc8f423828\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/4cfa4c37dcbcfd70866e856200ed8a2894cac578\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c4b9edd55987384a1f201d3d07ff71e448d79c1b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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  • 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.
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