{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "3b3009ea8abb713b022d94fba95ec270cf6e7eae"
            },
            {
              "fixed": "c06876d4fac38f35820946ee3b1be7d7da799cd4"
            },
            {
              "fixed": "f4251190e58b209999c1ba9e6d2976136a1be055"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.4.0"
            },
            {
              "fixed": "7.0.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63979.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: hand off the pinned file reference to accept_doit\n\nhandshake_req_next() removes the request from the per-net\npending list and drops hn_lock before handshake_nl_accept_doit()\nreads req-\u003ehr_sk-\u003esk_socket and dereferences sock-\u003efile (once in\nFD_PREPARE() and again in get_file()).  In that window a\nconsumer running tls_handshake_cancel() followed by sockfd_put()\n(svc_sock_free) or __fput_sync() (xs_reset_transport) releases\nsock-\u003efile.  sock_release() then runs sock_orphan(), zeroing\nsk_socket, and frees the struct socket.  The accept-side code\neither reads NULL through sk_socket or chases freed memory.\n\nThe submit-side sock_hold() does not prevent this.  sk_refcnt\nprotects struct sock, but struct socket and sock-\u003efile are\nindependently refcounted via the file descriptor the consumer\nowns.  Pinning sk leaves sock and sock-\u003efile unprotected.\n\nRetarget the accept-side dereferences at req-\u003ehr_file, which was\npinned at submit time, instead of req-\u003ehr_sk-\u003esk_socket-\u003efile.\nPinning on its own is not sufficient: a consumer that cancels\nbetween handshake_req_next() returning and accept_doit reaching\nFD_PREPARE() takes the !remove_pending() branch in\nhandshake_req_cancel() and drops hr_file before the accept side\ntakes its own reference.  Hand off an additional file reference\ninside handshake_req_next(), under hn_lock, so the accept side\noperates on a reference that no concurrent handshake_req_cancel()\ncan revoke.  FD_PREPARE() consumes that handed-off reference,\neither by transferring it to the new fd in fd_publish() or by\ndropping it in the cleanup destructor on error; the explicit\nget_file() that previously balanced FD_PREPARE() is therefore\nredundant and goes away.\n\nUpdate handshake_req_cancel_test2 and _test3 to simulate the\nFD_PREPARE() consumption with an fput() so the kunit file-count\nassertions stay balanced.",
  "id": "CVE-2026-63979",
  "modified": "2026-07-22T05:30:06.548127426Z",
  "published": "2026-07-19T14:56:03.177Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c06876d4fac38f35820946ee3b1be7d7da799cd4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f4251190e58b209999c1ba9e6d2976136a1be055"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63979.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63979"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "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": "net/handshake: hand off the pinned file reference to accept_doit"
}