{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "74d7970febf7e9005375aeda0df821d2edffc9f7"
            },
            {
              "fixed": "8c9a4f1327eb71efbf14842e7b8a6d965077eb67"
            },
            {
              "fixed": "54bab9ba5a9f156ffa9324fcbe5a356fd0242f95"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "019aae488dbc67c97a33db03652e20e2c9e3afa7"
            },
            {
              "last_affected": "6927ffe7479c72e7ebf885507227266a75f7c97d"
            },
            {
              "last_affected": "ef6cc1c465786b3e4e735d1ab8b616b3e94402df"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "5.15.145"
            },
            {
              "fixed": "5.16"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "6.1.71"
            },
            {
              "fixed": "6.2"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "6.3.10"
            },
            {
              "fixed": "6.4"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.4.0"
            },
            {
              "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-2026-64400.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: prevent path traversal bypass by restricting caseless retry\n\nksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path\nresolution within the share root. When a crafted path attempts to\nescape the share boundary using parent-directory components ('..'),\nvfs_path_parent_lookup() detects this and immediately fails,\nreturning -EXDEV.\n\nHowever, a bug exists in __ksmbd_vfs_kern_path() under caseless mode.\nThe function fails to intercept the -EXDEV error and erroneously\nfalls through to the caseless retry logic, which is intended only\nfor genuinely missing files. During this retry process, the path\nis reconstructed, leading to an unintended LOOKUP_BENEATH bypass\nthat allows write-capable users to create zero-length files or\ndirectories outside the exported share.\n\nFix this by ensuring that the execution only proceeds to the caseless\nlookup retry when the error is specifically -ENOENT. Any other errors,\nsuch as -EXDEV from a path traversal attempt, must be returned immediately.",
  "id": "CVE-2026-64400",
  "modified": "2026-07-28T03:55:42.136201302Z",
  "published": "2026-07-25T08:50:43.655Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/54bab9ba5a9f156ffa9324fcbe5a356fd0242f95"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8c9a4f1327eb71efbf14842e7b8a6d965077eb67"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64400.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64400"
    },
    {
      "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:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "ksmbd: prevent path traversal bypass by restricting caseless retry"
}