{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-98788",
  "modified": "2026-10-19T04:30:01Z",
  "upstream": [
    "CVE-2026-98788"
  ],
  "published": "2026-10-18T15:54:51Z",
  "summary": "futex: Fix private hash use-after-free on resize",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Fix private hash use-after-free on resize\n\npoll_state_synchronize_rcu(mm->futex.phash.batches) is used by\nfutex_ref_drop() to check that a grace period has passed since the\ncurrent hash was published. This relies on batches referencing a grace\nperiod which started after the hash pointer was assigned.\n\n__futex_pivot_hash() sets mmph->batches before it replaces mmph->hash:\n\n    scoped_guard(rcu) {\n            mmph->batches = get_state_synchronize_rcu();\n            rcu_assign_pointer(mmph->hash, new);\n    }\n\nThe scoped_guard(rcu) doesn't stop new grace periods from starting, and\nif one starts between those two assignments, futex_ref_drop() can move\nforward while a reader still holds a pointer to the old hash.\n\nFix things by setting mmph->batches after assigning mmph->hash.  The\nscoped_guard(rcu) isn't needed, so let's drop that as well.",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:13",
        "name": "linux"
      },
      "versions": [
        "1:6.18.29-1+rpt1",
        "1:6.18.33-1+rpt1",
        "1:6.18.34-1+rpt1",
        "1:6.18.39-1+rpt1",
        "1:6.18.50-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
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            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
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            "binary_version": "1:6.18.29-1+rpt1"
          },
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            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
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      "database_specific": {
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            "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc",
            "upstream_version": "6.18.29",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": null
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  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-98788"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/5d5dc18b3a9ac011619b7d3af4514bf9e9b6a6af"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f35e3b5784221654f9cdbd6222275a7fa203f6c3"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-10-18T15:54:51Z"
  }
}