{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "b326614ea2159ea5c835d320f261d05d080cd201"
            },
            {
              "fixed": "550cfb8a81181331d4d0f76ab75ee58a0bf41e3e"
            },
            {
              "fixed": "760ef2c579c2609cf17fb1cd5392f64d42d43d33"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.18.0"
            },
            {
              "fixed": "7.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64388.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb/client: fix chown/chgrp with SMB3 POSIX Extensions\n\nOwnership (chown) and group (chgrp) modifications were being ignored when\nmounting with SMB3 POSIX Extensions unless CIFS_MOUNT_CIFS_ACL or\nCIFS_MOUNT_MODE_FROM_SID were also explicitly set.\n\nFix this by checking for posix_extensions in cifs_setattr_nounix() when\nupdating UID and GID, ensuring that id_mode_to_cifs_acl() is called to map\nand set the ownership/group information on the server.",
  "id": "CVE-2026-64388",
  "modified": "2026-07-28T03:55:45.505556229Z",
  "published": "2026-07-25T08:50:36.202Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/550cfb8a81181331d4d0f76ab75ee58a0bf41e3e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/760ef2c579c2609cf17fb1cd5392f64d42d43d33"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64388.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64388"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "smb/client: fix chown/chgrp with SMB3 POSIX Extensions"
}