{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.0.12-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  tcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction  Blamed commit moved the TIME_WAIT-derived ISN from the skb control block to a per-CPU variable, assuming the value would always be consumed by tcp_conn_request() for the same packet that wrote it. That assumption is violated by multiple drop paths between the producer (__this_cpu_write(tcp_tw_isn, isn) in tcp_v{4,6}_rcv()) and the consumer (tcp_conn_request()):   - min_ttl / min_hopcount check  - xfrm policy check  - tcp_inbound_hash() MD5/AO mismatch  - tcp_filter() eBPF/SO_ATTACH_FILTER drop  - th-\u003esyn \u0026\u0026 th-\u003efin discard in tcp_rcv_state_process() TCP_LISTEN  - psp_sk_rx_policy_check() in tcp_v{4,6}_do_rcv()  - tcp_checksum_complete() in tcp_v{4,6}_do_rcv()  - tcp_v{4,6}_cookie_check() returning NULL  When a packet is dropped on any of these paths, tcp_tw_isn is left set.  The next SYN processed on the same CPU then consumes the non zero value in tcp_conn_request(), receiving a potentially predictable ISN.  This patch moves back tcp_tw_isn to skb-\u003ecb[], getting rid of the per-cpu variable.  Note that tcp_v{4,6}_fill_cb() do not set it.  Very litle impact on overall code size/complexity:  $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new add/remove: 0/0 grow/shrink: 2/1 up/down: 8/-15 (-7) Function                                     old     new   delta tcp_v6_rcv                                  3038    3042      +4 tcp_v4_rcv                                  3035    3039      +4 tcp_conn_request                            2938    2923     -15 Total: Before=24436060, After=24436053, chg -0.00%",
  "id": "DEBIAN-CVE-2026-64024",
  "modified": "2026-09-14T16:47:35.758405163Z",
  "published": "2026-07-19T16:17:42.413Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-64024"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-64024"
  ]
}