{
  "cveId": "CVE-2026-68100",
  "url": "https://patchblox.com/security/cve/CVE-2026-68100",
  "summary": "CVE-2026-68100 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-68100, released August 11, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "ksmbd: validate num_subauth when copying ACE in set_ntacl_dacl",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  ksmbd: validate num_subauth when copying ACE in set_ntacl_dacl  set_ntacl_dacl() copies each ACE from the attacker-controlled stored security descriptor verbatim into the response DACL without checking sid.num_subauth. The ACE bytes (including an unchecked num_subauth) originate from an authenticated SMB2_SET_INFO(SecInfo=DACL) that is stored raw via ksmbd_vfs_set_sd_xattr(); parse_dacl() rejects a bad ACE with \u0060break\u0060 rather than an error, so parse_sec_desc() still returns success and the malformed SD reaches the xattr intact.  On a subsequent SMB2_QUERY_INFO(SecInfo=DACL) for an inode carrying a POSIX access ACL, build_sec_desc() -\u003E set_ntacl_dacl() -\u003E set_posix_acl_entries_dacl() walks the copied ACEs and reads      ntace-\u003Esid.sub_auth[ntace-\u003Esid.num_subauth - 1]  with num_subauth taken straight from the stored SD. Since sub_auth[] is fixed at SID_MAX_SUB_AUTHORITIES (15), a crafted num_subauth (e.g. 255) drives an out-of-bounds heap read of ~1 KB with an offset fully controlled by an authenticated client.  The sibling functions already gate this field:   parse_dacl()    -- num_subauth == 0 || \u003E SID_MAX_SUB_AUTHORITIES   parse_sid()     -- num_subauth \u003E SID_MAX_SUB_AUTHORITIES   smb_copy_sid()  -- min_t(u8, num_subauth, SID_MAX_SUB_AUTHORITIES) set_ntacl_dacl() is the lone inconsistent path that omits the check.  Add the same num_subauth validation in set_ntacl_dacl() before copying the ACE, matching the gate already enforced by parse_dacl().",
  "published": "2026-08-10T13:19:54Z",
  "severity": "Moderate",
  "cvss": 8.1,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
  "epss": 0.00435,
  "epssPercentile": 0.38049,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-68100",
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "6.1.187-1",
      "fix": "DEBIAN-CVE-2026-68100",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-68100",
      "released": "2026-08-11T16:03:09Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.101-1",
      "fix": "DEBIAN-CVE-2026-68100",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-68100",
      "released": "2026-08-11T16:03:09Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.1.6-1",
      "fix": "DEBIAN-CVE-2026-68100",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-68100",
      "released": "2026-08-11T16:03:09Z"
    },
    {
      "platform": "linux",
      "product": "linux-6.12",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "6.12.101-1~deb12u1",
      "fix": "DEBIAN-CVE-2026-68100",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-68100",
      "released": "2026-08-11T16:03:09Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}