{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "fed979a7e082bd9f25f9002c3c4f8740dacd0bc8"
            },
            {
              "fixed": "51d18db392e5386a7bb9e816d611f14e600cca3c"
            },
            {
              "fixed": "aa3c0cab4b28c5007ec570c63e1d6ad6943ed0fd"
            },
            {
              "fixed": "945b4a4a54497db1dcb2f20ef801a84e884dac21"
            },
            {
              "fixed": "91b8a58c6ac15c7db6518f696389933282f88da7"
            },
            {
              "fixed": "0700f946659d0ab2352ec8a9b1c6fc74b13a27d7"
            },
            {
              "fixed": "ec457f9afe5ae9538bdcd58fd4cb442b9787e183"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "6.1.178"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.145"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.97"
            }
          ],
          "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-2026-64401.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: resolve SWN tcon from live registrations\n\ncifs_swn_notify() looks up a witness registration by id under\ncifs_swnreg_idr_mutex, drops the mutex, and then uses the registration's\ncached tcon pointer.  That pointer is not a lifetime reference, and it is\nnot a stable representative once cifs_get_swn_reg() lets multiple tcons\nfor the same net/share name share one registration id.\n\nA same-share second mount can keep the cifs_swn_reg alive after the first\ntcon unregisters and is freed.  The registration then still points at the\nfreed first tcon, so taking tc_lock or incrementing tc_count through\nswnreg-\u003etcon only moves the use-after-free earlier.  Taking tc_lock while\nholding cifs_swnreg_idr_mutex also violates the documented CIFS lock\norder.\n\nFix this by making the registration store only the stable witness\nidentity: id, net name, share name, and notify flags.  When a notify\narrives, copy that identity under cifs_swnreg_idr_mutex, drop the mutex,\nthen find and pin a live witness tcon that currently matches the net/share\npair under the normal cifs_tcp_ses_lock -\u003e tc_lock order.  The notification\npath uses that pinned tcon directly and drops the reference when done.\n\nRegistration and unregister messages now use the live tcon passed by the\ncaller instead of a cached tcon in the registration.  The final unregister\nsend is folded into cifs_swn_unregister() while the registration is still\nprotected by cifs_swnreg_idr_mutex.  This removes the previous\nfind/drop/reacquire raw-pointer window.  The release path only removes the\nidr entry and frees the stable identity strings.\n\nThis preserves the intended one-registration/many-tcon behavior: a\nregistration id represents a net/share pair, and notify handling acts on a\nlive representative selected at use time.  It also preserves CLIENT_MOVE\nordering for the representative tcon because the old-IP unregister is sent\nbefore cifs_swn_register() sends the new-IP register.",
  "id": "CVE-2026-64401",
  "modified": "2026-08-18T03:30:52.795896846Z",
  "published": "2026-07-25T08:50:44.361Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0700f946659d0ab2352ec8a9b1c6fc74b13a27d7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/51d18db392e5386a7bb9e816d611f14e600cca3c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/91b8a58c6ac15c7db6518f696389933282f88da7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/945b4a4a54497db1dcb2f20ef801a84e884dac21"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/aa3c0cab4b28c5007ec570c63e1d6ad6943ed0fd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ec457f9afe5ae9538bdcd58fd4cb442b9787e183"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64401.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64401"
    },
    {
      "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": "smb: client: resolve SWN tcon from live registrations"
}