Linux Distros Unpatched Vulnerability : CVE-2026-68173

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

include('compat.inc');

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  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/11");

  script_cve_id("CVE-2026-68173");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-68173");

  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.

  - In the Linux kernel, the following vulnerability has been resolved: ublk: wait on ublk_dev_ready() instead
    of ub->completion ub->completion is only re-armed by a successful START_USER_RECOVERY. If the ublk server
    sends END_USER_RECOVERY without one - e.g. its START failed with -EBUSY and the error was ignored - the
    wait is satisfied by the stale completion of the previous recovery cycle, and the device is marked LIVE
    and the requeue list kicked while the FETCH stream is still running and ubq->canceling is still set. The
    kick redispatches a previously requeued request, __ublk_queue_rq_common() sees ->canceling and parks it
    again via __ublk_abort_rq(), and after the last FETCH clears ->canceling nothing ever kicks the requeue
    list again: the request is stranded there while holding its tag. If it is the flush machinery's flush_rq,
    every subsequent fsync piles up in uninterruptible sleep and teardown hangs on tag draining. This matches
    a report of a lost PREFLUSH with ext4 on top of ublk after daemon crash recovery. ub->completion is an
    edge-triggered latch used as a proxy for the level condition every queue has fetched all I/O commands,
    which can regress (F_BATCH's UNPREP, daemon death) and whose re-arm can be skipped. Drop it and wait on
    the real condition instead: the new helper ublk_wait_dev_ready_and_lock() waits on ublk_dev_ready() via
    wait_var_event_interruptible(), woken from ublk_mark_io_ready(), then re-checks it under ub->mutex,
    waiting again on regression, and returns with the mutex held and readiness guaranteed. Readiness becomes
    true in the same ub->mutex critical section that clears the last queue's ->canceling, so END_USER_RECOVERY
    marks the device LIVE and kicks the requeue list strictly after ->canceling clears. The wait stays
    interruptible, so a server whose daemon died can still be signalled out. For ublk_ctrl_start_dev() this
    replaces the fail-fast -EINVAL on an F_BATCH ready->UNPREP regression with waiting until the device is
    ready again. (CVE-2026-68173)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/cve-2026-68173");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_attribute(attribute:"risk_factor", value:"Medium");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
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  script_set_attribute(attribute:"vuln_publication_date", value:"2026/08/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/11");

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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/RedHat/rpm-list"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "kernel"},
          {"reference": "kernel-64k"},
          {"reference": "kernel-64k-core"},
          {"reference": "kernel-64k-debug"},
          {"reference": "kernel-64k-debug-core"},
          {"reference": "kernel-64k-debug-devel"},
          {"reference": "kernel-64k-debug-devel-matched"},
          {"reference": "kernel-64k-debug-modules"},
          {"reference": "kernel-64k-debug-modules-core"},
          {"reference": "kernel-64k-debug-modules-extra"},
          {"reference": "kernel-64k-devel"},
          {"reference": "kernel-64k-devel-matched"},
          {"reference": "kernel-64k-modules"},
          {"reference": "kernel-64k-modules-core"},
          {"reference": "kernel-64k-modules-extra"},
          {"reference": "kernel-abi-stablelists"},
          {"reference": "kernel-core"},
          {"reference": "kernel-debug"},
          {"reference": "kernel-debug-core"},
          {"reference": "kernel-debug-devel"},
          {"reference": "kernel-debug-devel-matched"},
          {"reference": "kernel-debug-modules"},
          {"reference": "kernel-debug-modules-core"},
          {"reference": "kernel-debug-modules-extra"},
          {"reference": "kernel-debug-uki-virt"},
          {"reference": "kernel-devel"},
          {"reference": "kernel-devel-matched"},
          {"reference": "kernel-doc"},
          {"reference": "kernel-modules"},
          {"reference": "kernel-modules-core"},
          {"reference": "kernel-modules-extra"},
          {"reference": "kernel-modules-extra-matched"},
          {"reference": "kernel-rt"},
          {"reference": "kernel-rt-64k"},
          {"reference": "kernel-rt-64k-core"},
          {"reference": "kernel-rt-64k-debug"},
          {"reference": "kernel-rt-64k-debug-core"},
          {"reference": "kernel-rt-64k-debug-devel"},
          {"reference": "kernel-rt-64k-debug-modules"},
          {"reference": "kernel-rt-64k-debug-modules-core"},
          {"reference": "kernel-rt-64k-debug-modules-extra"},
          {"reference": "kernel-rt-64k-devel"},
          {"reference": "kernel-rt-64k-modules"},
          {"reference": "kernel-rt-64k-modules-core"},
          {"reference": "kernel-rt-64k-modules-extra"},
          {"reference": "kernel-rt-core"},
          {"reference": "kernel-rt-debug"},
          {"reference": "kernel-rt-debug-core"},
          {"reference": "kernel-rt-debug-devel"},
          {"reference": "kernel-rt-debug-kvm"},
          {"reference": "kernel-rt-debug-modules"},
          {"reference": "kernel-rt-debug-modules-core"},
          {"reference": "kernel-rt-debug-modules-extra"},
          {"reference": "kernel-rt-devel"},
          {"reference": "kernel-rt-kvm"},
          {"reference": "kernel-rt-modules"},
          {"reference": "kernel-rt-modules-core"},
          {"reference": "kernel-rt-modules-extra"},
          {"reference": "kernel-tools"},
          {"reference": "kernel-tools-libs"},
          {"reference": "kernel-tools-libs-devel"},
          {"reference": "kernel-uki-virt"},
          {"reference": "kernel-uki-virt-addons"},
          {"reference": "kernel-zfcpdump"},
          {"reference": "kernel-zfcpdump-core"},
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          {"reference": "libperf"},
          {"reference": "perf"},
          {"reference": "python3-perf"},
          {"reference": "rtla"},
          {"reference": "rv"}
        ]
      }
    ]
  }
};

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');
}