{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "e4eb295d38b57f4d4b956942a48887eb252d97c6"
            },
            {
              "fixed": "672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e"
            },
            {
              "fixed": "033bc80019f07d158630df4e69b19a49010f54f1"
            },
            {
              "fixed": "6343c1da561962688f203362d80d6a3bfa39fa1b"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.12"
            },
            {
              "fixed": "6.18.51"
            }
          ],
          "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-2026-89633.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()\n\ncoalesce_t2() computes data pointers directly from server-supplied\nDataOffset fields with no validation against buffer bounds:\n\n  data_area_of_tgt = (char *)\u0026pSMBt-\u003ehdr.Protocol +\n                     get_unaligned_le16(\u0026pSMBt-\u003et2_rsp.DataOffset);\n  data_area_of_src = (char *)\u0026pSMBs-\u003ehdr.Protocol +\n                     get_unaligned_le16(\u0026pSMBs-\u003et2_rsp.DataOffset);\n  data_area_of_tgt += total_in_tgt;\n  ...\n  memcpy(data_area_of_tgt, data_area_of_src, total_in_src);\n\nA small DataOffset can push a pointer below the actual byte area,\noverwriting header fields; a large one can push it past the buffer\nend, causing out-of-bounds heap reads (source) or writes (target).\nThe BCC overflow guard does not prevent this: BCC reflects how much\ndata is present, while DataOffset controls where in the buffer it\nstarts.\n\nThe \"validate target area\" comment present since the function was\nfirst written in 2005 was a placeholder that was never implemented.\n\nAdd lower- and upper-bound checks for both data pointers before the\nmemcpy, and before any target header fields are modified.",
  "id": "CVE-2026-89633",
  "modified": "2026-09-15T03:31:00.638920950Z",
  "published": "2026-09-11T19:45:28.083Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/033bc80019f07d158630df4e69b19a49010f54f1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89633.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89633"
    },
    {
      "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:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()"
}