{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-99133",
  "modified": "2026-10-29T05:30:01Z",
  "upstream": [
    "CVE-2026-99133"
  ],
  "published": "2026-10-28T11:36:32Z",
  "summary": "net/iucv: fix the recvmsg window update",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/iucv: fix the recvmsg window update\n\niucv_sock_recvmsg() sends the HiperSockets-only AF_IUCV_FLAG_WIN without\ntesting the transport, so on a classic z/VM socket iucv_send_ctrl() sizes\nthe skb through a NULL iucv->hs_dev. SO_MSGLIMIT accepts 1, so msglimit / 2\nis zero and one recvmsg() on its own socket is enough for an unprivileged\nprocess to take a spurious disconnect.\n\nIt also calls iucv_send_ctrl() under spin_lock_bh(&message_q.lock), which\nallocates GFP_KERNEL inside a section the code treats as atomic. Sending\noutside that lock lets two recvmsg() reach afiucv_hs_send() at once, where\nmsg_recv is sampled for the advertised window and subtracted after\ndev_queue_xmit() -- and sendmsg reaches that counter under lock_sock()\nwhile recvmsg holds no socket lock, so both can subtract the same value,\nthe counter goes negative and the credit reaches the peer twice.\n\nTest the transport, claim the credit with atomic_xchg() after the last\nerror exit and hand it back if the transmit fails, and send once the lock\nis dropped.",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": null,
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-99133"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8f2efa742f4cfe7dd756154f8bc07350dbe3ec92"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/fe7393a627db2d093e8c0cae69d619b30fefae5f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/fa5acd038ea657ad5033713d6916214cbd349151"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-10-28T11:36:32Z"
  }
}