{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "3b3009ea8abb713b022d94fba95ec270cf6e7eae"
            },
            {
              "fixed": "9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd"
            },
            {
              "fixed": "8c35539db0ab0bfa1ea44efab00b053261a69469"
            },
            {
              "fixed": "ea5fe6a73ca57e5150b8a38b341aef2636eb72f0"
            }
          ],
          "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": "6.12.93"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "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-2026-63978.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: Drain pending requests at net namespace exit\n\nThe arguments to list_splice_init() in handshake_net_exit() are\nreversed. The call moves the local empty \"requests\" list onto\nhn-\u003ehn_requests, leaving the local list empty, so the subsequent\ndrain loop runs zero iterations. Pending handshake requests that\nhad not yet been accepted are not torn down when the net namespace\nis destroyed; each one keeps a reference on a socket file and on\nthe handshake_req allocation.\n\nPass the source and destination in the documented order\n(list_splice_init(list, head) moves list onto head) so the pending\nlist is transferred to the local scratch list and drained through\nhandshake_complete().\n\nFixing the splice direction exposes a list-corruption race. After\nthe splice each req-\u003ehr_list still has non-empty link pointers,\nthreading the stack-local scratch list rather than hn_requests.\nA concurrent handshake_req_cancel() -- for example, from sunrpc's\nTLS timeout on a kernel socket whose netns reference was not\ntaken -- finds the request through the rhashtable, calls\nremove_pending(), and sees !list_empty(\u0026req-\u003ehr_list).\n__remove_pending_locked() then list_del_init()s an entry off the\nscratch list while the drain iterates, corrupting it. The same\ncall arriving after the drain loop has run list_del() on an\nentry hits LIST_POISON instead.\n\nHave remove_pending() check HANDSHAKE_F_NET_DRAINING under\nhn_lock and report not-found when drain is in progress. The\ndrain has already taken ownership; handshake_complete()'s existing\ntest_and_set on HANDSHAKE_F_REQ_COMPLETED still arbitrates\nbetween drain and cancel for who calls the consumer's hp_done. Use\nlist_del_init() rather than list_del() in the drain so req-\u003ehr_list\ndoes not carry LIST_POISON after drain releases the entry.\n\nThe DRAINING guard in remove_pending() makes cancel return false,\nbut cancel still falls through to test_and_set_bit on\nHANDSHAKE_F_REQ_COMPLETED and drops the request's hr_file reference.\nWithout another pin, if that is the last reference, sk_destruct frees\nthe request while it is still linked on the drain loop's local list.\nPin each request's hr_file under hn_lock before releasing the list,\nand drop that drain pin after the loop finishes with the request.",
  "id": "CVE-2026-63978",
  "modified": "2026-07-21T03:42:06.046529501Z",
  "published": "2026-07-19T14:56:02.484Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8c35539db0ab0bfa1ea44efab00b053261a69469"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ea5fe6a73ca57e5150b8a38b341aef2636eb72f0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63978.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63978"
    },
    {
      "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: Drain pending requests at net namespace exit"
}