{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "316cf94a910f6f93d43cc574359d163ccae098a3"
            },
            {
              "fixed": "9eed72e9534b10a6d9f8f5146feff3db53aebdba"
            },
            {
              "fixed": "5e6533a683f6a851158d9f33fb4ea8f4f25d7f84"
            },
            {
              "fixed": "730d0bb19507b9e19c2fe5343109ac618e2fbce5"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.6.0"
            },
            {
              "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-2026-89637.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2\n\nWhen a valid primary TRANSACT2 response has been received (mid-\u003eresp_buf\nset, mid-\u003emultiRsp true) and a subsequent secondary response causes\ncifs_check_trans2() to return false -- either because the SMB header is\ninvalid (malformed != 0) or because check2ndT2() rejects the PDU --\nhandle_mid() overwrites mid-\u003eresp_buf with the new buffer (leaking the\nprimary buffer) and, because mid-\u003emultiRsp is set, skips the\nserver-\u003esmallbuf/bigbuf NULL-out.  When the user thread frees\nmid-\u003eresp_buf, server-\u003esmallbuf or server-\u003ebigbuf is left dangling; the\ndemux thread reuses it for the next packet, resulting in a use-after-free.\n\nCombine both early-exit conditions and, when mid-\u003emultiRsp is already\nset, abort the pending transaction inline: set multiEnd, call\ndequeue_mid() with malformed=true, and return true so handle_mid() exits\nwithout touching mid-\u003eresp_buf or the server buffer pointers.",
  "id": "CVE-2026-89637",
  "modified": "2026-09-15T03:30:57.195049157Z",
  "published": "2026-09-11T19:45:31.048Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5e6533a683f6a851158d9f33fb4ea8f4f25d7f84"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/730d0bb19507b9e19c2fe5343109ac618e2fbce5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9eed72e9534b10a6d9f8f5146feff3db53aebdba"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89637.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89637"
    },
    {
      "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 UAF and buffer leak in cifs_check_trans2() for malformed secondary T2"
}