{
  "cveId": "CVE-2026-63909",
  "url": "https://patchblox.com/security/cve/CVE-2026-63909",
  "summary": "CVE-2026-63909 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-63909, released July 20, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  ksmbd: OOB read regression in smb_check_perm_dac...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  ksmbd: OOB read regression in smb_check_perm_dacl() ACE-walk loops  Commit d07b26f39246 (\u0022ksmbd: require minimum ACE size in smb_check_perm_dacl()\u0022) introduced a transposed bounds check:      if (offsetof(struct smb_ace, sid) \u002B aces_size \u003C CIFS_SID_BASE_SIZE)  Since offsetof(..sid) is 8 and CIFS_SID_BASE_SIZE is 8, this evaluates to \u0060aces_size \u003C 0\u0060. Because \u0060aces_size\u0060 is always non-negative, this check becomes dead code and never breaks the loop.  Worse, that commit removed the old 4-byte guard, meaning the loop now reads \u0060ace-\u003Esize\u0060 (offset 2) even when \u0060aces_size\u0060 is 0-3 bytes. This re-opens a 2-byte heap out-of-bounds (OOB) read past the pntsd allocation during subsequent SMB2_CREATE operations.  Fix this by properly transposing the comparison to require at least 16 bytes (8-byte offset \u002B 8-byte SID base), matching the correct form used in smb_inherit_dacl().",
  "published": "2026-07-19T16:17:08Z",
  "severity": "high",
  "cvss": 8.1,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
  "epss": 0.00628,
  "epssPercentile": 0.50405,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.94-1",
      "fix": "DEBIAN-CVE-2026-63909",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-63909",
      "released": "2026-07-20T12:58:36Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.0.12-1",
      "fix": "DEBIAN-CVE-2026-63909",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-63909",
      "released": "2026-07-20T12:58:36Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-10T13:56:55Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}