Linux Distros Unpatched Vulnerability : CVE-2026-72473

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(335543);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/15");

  script_cve_id("CVE-2026-72473");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-72473");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - xprtrdma: Decouple req recycling from RPC completion rl_kref formerly served two distinct lifetimes
    through a single refcount: it gated when a Reply could wake its RPC task, and it gated when an rpcrdma_req
    could return to its free pool. The marshal path took the Send-side reference only when SGEs needed DMA-
    unmap (sc_unmap_count > 0), which made a Send carrying only pre-registered buffers an exception: the Reply
    handler dropped rl_kref from 1 to 0 and freed the req while the HCA might still be DMA-reading from its
    send buffer. Give rl_kref a narrower job. The RPC layer takes one reference when slot allocation hands a
    req out. rpcrdma_prepare_send_sges() takes a Send-side reference unconditionally after WR preparation
    succeeds. xprt_rdma_free_slot() and xprt_rdma_bc_free_rqst() drop the RPC-layer reference;
    rpcrdma_sendctx_unmap() drops the Send-side reference. The req returns to its free pool only after both
    owners have signed off. The existing kref_init(&req->rl_kref) call in rpcrdma_prepare_send_sges() is
    removed. Initialization moves to the slot-allocation paths (xprt_rdma_alloc_slot and rpcrdma_bc_rqst_get),
    and the release callback re-arms rl_kref before the req returns to a free pool. A re-init in the marshal
    path would discard the RPC-layer reference that already exists on entry. Three invariants follow: - Any
    rpcrdma_req held by an rpc_rqst has rl_kref >= 1. xprt_rdma_alloc_slot(), rpcrdma_bc_rqst_get(), and the
    backlog-wake branch in xprt_rdma_alloc_slot() each kref_init rl_kref before publishing the req. Without
    this invariant, an RPC task that aborts between slot allocation and marshal (gss_refresh failure or signal
    during call_connect, for example) would drive xprt_release() -> xprt_rdma_free_slot() -> kref_put against
    a refcount of zero, saturating refcount_t and stranding the slot. - The Send-side reference is taken only
    after WR prep succeeds. A mapping failure in rpcrdma_prepare_send_sges() runs rpcrdma_sendctx_cancel(),
    which DMA-unmaps the sendctx and clears sc_req without touching rl_kref. The sendctx ring walks in
    rpcrdma_sendctx_put_locked() and rpcrdma_sendctxs_destroy() skip entries with sc_req == NULL, so a burst
    of -EIO marshal failures cannot hold reqs off rb_send_bufs. - The release callback re-arms rl_kref so the
    next consumer enters with the invariant satisfied. Replies now complete the RPC directly.
    rpcrdma_reply_handler() calls rpcrdma_complete_rqst() in place of kref_put on the non-LocalInv branch. The
    LocalInv branch already completes the RPC from frwr_unmap_async() and is unaffected. Because Send-side
    references can now outlive RPC completion, connection teardown drains sendctx entries whose unsignaled
    Sends never had a later signaled completion to walk the ring. rpcrdma_sendctxs_destroy() walks the active
    range and runs rpcrdma_sendctx_unmap() on each entry with a non-NULL sc_req before the request buffers are
    reset, and is moved ahead of rpcrdma_reqs_reset() in rpcrdma_xprt_disconnect() so the reqs are still in
    their pre-reset state when the Send-side refs are released. The drain creates a teardown-ordering hazard
    on the backchannel path. With the new lifetime, releasing a bc_prealloc req from rpcrdma_req_release() re-
    adds it to bc_pa_list. The disconnect in xprt_rdma_destroy() runs after xprt_destroy_backchannel() has
    already emptied bc_pa_list, so the drained reqs would otherwise leak. xprt_rdma_destroy() now runs
    xprt_rdma_bc_destroy(xprt, 0) a second time after the disconnect to reclaim them. (CVE-2026-72473)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-72473");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-72473");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_unpatched", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/08/15");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/15");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:11.0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:linux");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl", "set_linux_os_id.nasl");
  script_require_keys("Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched", "Host/OS/identifier");
  script_require_ports("Host/OS/Debian Linux-11");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/Debian/dpkg-l"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Debian Linux-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "bpftool"},
          {"reference": "btrfs-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "cdrom-core-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "hyperv-daemons"},
          {"reference": "kernel-image-5.10.0-32-alpha-generic-di"},
          {"reference": "libcpupower-dev"},
          {"reference": "libcpupower1"},
          {"reference": "linux-bootwrapper-5.10.0"},
          {"reference": "linux-config-5.10"},
          {"reference": "linux-cpupower"},
          {"reference": "linux-doc"},
          {"reference": "linux-doc-5.10"},
          {"reference": "linux-headers-5.10.0"},
          {"reference": "linux-kbuild-5.10"},
          {"reference": "linux-libc-dev"},
          {"reference": "linux-perf"},
          {"reference": "linux-perf-5.10"},
          {"reference": "linux-source"},
          {"reference": "linux-source-5.10"},
          {"reference": "linux-support-5.10.0"},
          {"reference": "loop-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "nic-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "nic-shared-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "nic-wireless-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "pata-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "ppp-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "scsi-core-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "scsi-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "scsi-nic-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "serial-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "usb-serial-modules-5.10.0-32-alpha-generic-di"},
          {"reference": "usbip"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (!empty_or_null(third_party_support)) {
    var third_party_vendors = distro_constraints_values['third_party'];
    if (!empty_or_null(third_party_vendors)) {
        var vendor;
        foreach vendor (third_party_vendors) {
            if (vendor == third_party_support) exit(0, 'A third party management patch is available for this vulnerability from ' + vendor + '.\n');
        }
    }
}

var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}