{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "06c5c97293e3fca99ce15da157068edf45a7c6e4"
            },
            {
              "fixed": "fa6590dfd16ab55f03b658b079072ace3504825e"
            },
            {
              "fixed": "250ec14932d5cfe102f68a57892bb566eee7f83e"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "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-2026-89678.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix partial-write detection in nfsd_direct_write\n\nnfsd_direct_write() walks a list of write segments and, after each\nvfs_iocb_iter_write(), tries to detect a short write so the loop can\nstop before placing the next segment at a wrong file offset:\n\n    host_err = vfs_iocb_iter_write(file, kiocb, \u0026segments[i].iter);\n    if (host_err \u003c 0)\n            return host_err;\n    *cnt += host_err;\n    if (host_err \u003c segments[i].iter.count)\n            break;\t/* partial write */\n\nvfs_iocb_iter_write() runs the iter through -\u003ewrite_iter(), which\nadvances the iter by the number of bytes written. By the time the\ncheck runs, segments[i].iter.count is the residual, not the original\nrequest length:\n\n    before write_iter: iter.count == original_len\n    after  write_iter: iter.count == original_len - host_err\n\nThe condition then reduces to host_err \u003c original_len - host_err, so\nthe break fires only when less than half of the segment was written.\nAny short write completing between 50% and 99% of the segment slips\nthrough; the loop advances to the next segment with kiocb-\u003eki_pos\nonly bumped by the short amount, writing the next segment's payload\nat the wrong offset and over-reporting *cnt to the NFS client.\n\nSnapshot the segment's byte count before the write and compare\nhost_err against that snapshot so any short write breaks the loop.",
  "id": "CVE-2026-89678",
  "modified": "2026-09-15T03:30:52.565829228Z",
  "published": "2026-09-11T19:46:02.184Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/250ec14932d5cfe102f68a57892bb566eee7f83e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fa6590dfd16ab55f03b658b079072ace3504825e"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89678.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89678"
    },
    {
      "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:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "nfsd: fix partial-write detection in nfsd_direct_write"
}