{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2025-21669",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2025-21669"
  ],
  "published": "2025-01-31T11:31:15Z",
  "summary": "vsock/virtio: discard packets if the transport changes",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/virtio: discard packets if the transport changes\n\nIf the socket has been de-assigned or assigned to another transport,\nwe must discard any packets received because they are not expected\nand would cause issues when we access vsk->transport.\n\nA possible scenario is described by Hyunwoo Kim in the attached link,\nwhere after a first connect() interrupted by a signal, and a second\nconnect() failed, we can find `vsk->transport` at NULL, leading to a\nNULL pointer dereference.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
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  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-21669"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/18a7fc371d1dbf8deff16c2dd9292bcc73f43040"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6486915fa661584d70e8e7e4068c6c075c67dd6d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/88244163bc7e7b0ce9dd7bf4c8a563b41525c3ee"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d88b249e14bd0ee1e46bbe4f456e22e01b8c68de"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/677579b641af109613564460a4e3bdcb16850b61"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2cb7c756f605ec02ffe562fb26828e4bcc5fdfc1"
    }
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  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T12:19:11Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerability is reached through AF_VSOCK socket syscalls (`connect()`) plus packets delivered by the local `vsock_loopback` transport, all from a local process. Per kernel scoring guidance vsock is Local.\nAC:L - The attacker controls every element: both `connect()` calls, the interrupting signal (self-delivered via `alarm()`/`pthread_kill()`), the peer socket that times the RESPONSE, and the RST/SHUTDOWN packet, and the sequence can be retried indefinitely.\nPR:L - `vsock_create()` performs no capability check and `CONFIG_VSOCKETS_LOOPBACK` is `default y`, so any unprivileged local user can create AF_VSOCK sockets, auto-bind an ephemeral port, and inject loopback packets.\nUI:N - The entire sequence \u2014 double connect, signal, packet injection \u2014 is performed by the attacker's own process with no victim action required.\nS:U - The corruption and crash are confined to the kernel of the machine running the attacker's process; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - When the socket has been reassigned to a non-virtio transport, `vsk->trans` is type-confused as `struct virtio_vsock_sock`, letting the receive path read and act on mistyped heap state (mistyped `sk_buff_head` in `virtio_transport_recv_enqueue()`, `container_of` on a non-`virtio_transport` ops struct), which is leverageable for arbitrary kernel memory disclosure.\nI:H - The same type confusion writes two fully attacker-controlled 32-bit header values (`buf_alloc`/`fwd_cnt`) into the middle of a differently-typed heap object (over `qpair`/`produce_size` in `struct vmci_transport`) and performs an indirect call through `t_ops->send_pkt` derived from a bogus `container_of`, giving a controlled-write and control-flow hijack primitive.\nA:H - The confirmed and reported impact is a NULL pointer dereference at `vsk->transport->stream_has_data()` while the socket lock is held, producing a kernel oops/panic that an unprivileged user can trigger on demand."
    }
  }
}