{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "af22f94ae02ab9dd4fd7fe628c8434a59cc293be"
            },
            {
              "fixed": "4817c8974315b666e895b7d1bb83cd3664c323b1"
            },
            {
              "fixed": "cb148a2762d644bff1894728e8835a9a4b84f9ea"
            },
            {
              "fixed": "30fdf4df6c3c00efec947e4ddf97f0fdd4473628"
            },
            {
              "fixed": "22c1fd1355ad4ca27aa7f0fa02719122dd92d9de"
            },
            {
              "fixed": "6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230"
            },
            {
              "fixed": "a937e92c1d00534b5c2e3e9f4381b7e988180797"
            },
            {
              "fixed": "e36501b7d4abdcd6d69a7cb901b2f286b7a3d041"
            },
            {
              "fixed": "5140f099ecd8a2f2808b7f7b720ee1bad8468974"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.24"
            },
            {
              "fixed": "5.10.261"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.212"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.178"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.145"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.96"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.39"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "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-2026-64298.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4: include MAY_WRITE in open permission mask for O_TRUNC\n\nPOSIX requires write permission to truncate a file, so an open() that\nspecifies O_TRUNC must be authorized for write access regardless of the\nO_ACCMODE access mode.\n\nnfs_open_permission_mask() builds the access mask passed to\nnfs_may_open(), which is the local authorization gate for OPENs the\nclient serves itself from a cached write delegation via the\ncan_open_delegated() path in nfs4_try_open_cached().  The mask is\nderived from O_ACCMODE alone, so an open(O_RDONLY | O_TRUNC) against a\nfile the caller cannot write requests only MAY_READ and passes the\nlocal check.  The OPEN is then satisfied locally and the truncation is\nissued to the server as a SETATTR(size=0) over the delegation stateid,\nwhich the server accepts under standard write-delegation semantics.\nPOSIX requires that this open fail with EACCES.\n\nInclude MAY_WRITE in the mask whenever O_TRUNC is set so the local\ncheck matches the access the server would have enforced.",
  "id": "CVE-2026-64298",
  "modified": "2026-07-28T03:55:44.710402112Z",
  "published": "2026-07-25T08:49:35.101Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/22c1fd1355ad4ca27aa7f0fa02719122dd92d9de"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/30fdf4df6c3c00efec947e4ddf97f0fdd4473628"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4817c8974315b666e895b7d1bb83cd3664c323b1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5140f099ecd8a2f2808b7f7b720ee1bad8468974"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a937e92c1d00534b5c2e3e9f4381b7e988180797"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb148a2762d644bff1894728e8835a9a4b84f9ea"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e36501b7d4abdcd6d69a7cb901b2f286b7a3d041"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64298.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64298"
    },
    {
      "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:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "NFSv4: include MAY_WRITE in open permission mask for O_TRUNC"
}