{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "110fee6b9bb58a5c50047fc2594d415f741b591e"
            },
            {
              "fixed": "4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4"
            },
            {
              "fixed": "4bea15d9c7683218f57b8c1f5f0aa75cab76af8d"
            },
            {
              "fixed": "b96db32fed8dfb2478d7c208f89bf383beed1535"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.18.0"
            },
            {
              "fixed": "6.18.50"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89641.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size()\n\nWhen the else branch of cifs_file_set_size() finds a writable file handle\nvia find_writable_file(), it borrows tcon and server from the handle's\ntlink, attempts the handle-based set_file_size() RPC, and then releases\nthe handle with cifsFileInfo_put().\n\nIf set_file_size() fails, execution falls through to the path-based\nfallback, which reuses the borrowed tcon and server under the\n\"if (tcon == NULL)\" guard.  Since tcon is not NULL at that point, the\nguard is skipped.  If cifsFileInfo_put() dropped the last reference on a\ntlink that was already removed from the tlink tree (TCON_LINK_IN_TREE\ncleared, as happens during reconnection or session teardown),\ncifs_put_tlink() will have freed tcon; the subsequent set_path_size()\ncall is then a use-after-free.\n\nSetting tcon = NULL after cifsFileInfo_put() causes the existing guard\nto take the cifs_sb_tlink() path, which acquires a fresh reference for\nthe path-based operation or fails cleanly if the session is gone.",
  "id": "CVE-2026-89641",
  "modified": "2026-09-15T03:31:00.851401194Z",
  "published": "2026-09-11T19:45:34.036Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4bea15d9c7683218f57b8c1f5f0aa75cab76af8d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b96db32fed8dfb2478d7c208f89bf383beed1535"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89641.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89641"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "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": "cifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size()"
}