Unity Linux 20.1050a Security Update: kernel (UTSA-2026-100326)

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

include('compat.inc');

if (description)
{
  script_id(336041);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/17");

  script_cve_id("CVE-2026-31469");

  script_name(english:"Unity Linux 20.1050a Security Update: kernel (UTSA-2026-100326)");

  script_set_attribute(attribute:"synopsis", value:
"The Unity Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the
UTSA-2026-100326 advisory.

    In the Linux kernel, the following vulnerability has been resolved:

    virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false

    A UAF issue occurs when the virtio_net driver is configured with napi_tx=N
    and the device's IFF_XMIT_DST_RELEASE flag is cleared
    (e.g., during the configuration of tc route filter rules).

    When IFF_XMIT_DST_RELEASE is removed from the net_device, the network stack
    expects the driver to hold the reference to skb->dst until the packet
    is fully transmitted and freed. In virtio_net with napi_tx=N,
    skbs may remain in the virtio transmit ring for an extended period.

    If the network namespace is destroyed while these skbs are still pending,
    the corresponding dst_ops structure has freed. When a subsequent packet
    is transmitted, free_old_xmit() is triggered to clean up old skbs.
    It then calls dst_release() on the skb associated with the stale dst_entry.
    Since the dst_ops (referenced by the dst_entry) has already been freed,
    a UAF kernel paging request occurs.

    fix it by adds skb_dst_drop(skb) in start_xmit to explicitly release
    the dst reference before the skb is queued in virtio_net.

    Call Trace:
     Unable to handle kernel paging request at virtual address ffff80007e150000
     CPU: 2 UID: 0 PID: 6236 Comm: ping Kdump: loaded Not tainted 7.0.0-rc1+ #6 PREEMPT
      ...
      percpu_counter_add_batch+0x3c/0x158 lib/percpu_counter.c:98 (P)
      dst_release+0xe0/0x110  net/core/dst.c:177
      skb_release_head_state+0xe8/0x108 net/core/skbuff.c:1177
      sk_skb_reason_drop+0x54/0x2d8 net/core/skbuff.c:1255
      dev_kfree_skb_any_reason+0x64/0x78 net/core/dev.c:3469
      napi_consume_skb+0x1c4/0x3a0 net/core/skbuff.c:1527
      __free_old_xmit+0x164/0x230  drivers/net/virtio_net.c:611 [virtio_net]
      free_old_xmit drivers/net/virtio_net.c:1081 [virtio_net]
      start_xmit+0x7c/0x530 drivers/net/virtio_net.c:3329 [virtio_net]
      ...

    Reproduction Steps:
    NETDEV=enp3s0

    config_qdisc_route_filter() {
        tc qdisc del dev $NETDEV root
        tc qdisc add dev $NETDEV root handle 1: prio
        tc filter add dev $NETDEV parent 1:0 \
            protocol ip prio 100 route to 100 flowid 1:1
        ip route add 192.168.1.100/32 dev $NETDEV realm 100
    }

    test_ns() {
        ip netns add testns
        ip link set $NETDEV netns testns
        ip netns exec testns ifconfig $NETDEV  10.0.32.46/24
        ip netns exec testns ping -c 1 10.0.32.1
        ip netns del testns
    }

    config_qdisc_route_filter

    test_ns
    sleep 2
    test_ns

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  # https://src.uniontech.com/#/security_advisory_detail?utsa_id=UTSA-2026-100326
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?0a75d220");
  # https://lore.kernel.org/linux-cve-announce/2026042254-CVE-2026-31469-65d8@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?5cec1780");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-31469");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-31469");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/04/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/17");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Unity Linux Local Security Checks");

  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");
  script_require_keys("Host/local_checks_enabled", "Host/UOS-Server/release", "Host/UOS-Server/rpm-list", "Host/cpu");

  exit(0);
}
include('rpm2.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'UOS Server' >!< os_product) audit(AUDIT_OS_NOT, 'UOS Server');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'UOS Server');
if (! preg(pattern:"^20.1050a([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'UOS Server 20.1050a', 'UOS Server ' + os_version);

if (!get_kb_item('Host/UOS-Server/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('aarch64' >!< cpu && 'amd64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'UOS Server', cpu);


var constraints = [
  {
    'release': '20',
    'sp': '1050a',
    'pkgs': [
      {'reference':'kernel-5.10.0-27.18.uelc20', 'sp':'1050a', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-5.10.0-27.18.uelc20', 'sp':'1050a', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-5.10.0-27.18.uelc20', 'sp':'1050a', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}


if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'kernel');
}