Unity Linux 20.1050a Security Update: kernel (UTSA-2026-053271)

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

include('compat.inc');

if (description)
{
  script_id(343201);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/06");

  script_cve_id("CVE-2025-68813");

  script_name(english:"Unity Linux 20.1050a Security Update: kernel (UTSA-2026-053271)");

  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-2026-053271 advisory.

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

    ipvs: fix ipv4 null-ptr-deref in route error path

    The IPv4 code path in __ip_vs_get_out_rt() calls dst_link_failure()
    without ensuring skb->dev is set, leading to a NULL pointer dereference
    in fib_compute_spec_dst() when ipv4_link_failure() attempts to send
    ICMP destination unreachable messages.

    The issue emerged after commit ed0de45a1008 (ipv4: recompile ip options
    in ipv4_link_failure) started calling __ip_options_compile() from
    ipv4_link_failure(). This code path eventually calls fib_compute_spec_dst()
    which dereferences skb->dev. An attempt was made to fix the NULL skb->dev
    dereference in commit 0113d9c9d1cc (ipv4: fix null-deref in
    ipv4_link_failure), but it only addressed the immediate dev_net(skb->dev)
    dereference by using a fallback device. The fix was incomplete because
    fib_compute_spec_dst() later in the call chain still accesses skb->dev
    directly, which remains NULL when IPVS calls dst_link_failure().

    The crash occurs when:
    1. IPVS processes a packet in NAT mode with a misconfigured destination
    2. Route lookup fails in __ip_vs_get_out_rt() before establishing a route
    3. The error path calls dst_link_failure(skb) with skb->dev == NULL
    4. ipv4_link_failure()  ipv4_send_dest_unreach() 
       __ip_options_compile()  fib_compute_spec_dst()
    5. fib_compute_spec_dst() dereferences NULL skb->dev

    Apply the same fix used for IPv6 in commit 326bf17ea5d4 (ipvs: fix
    ipv6 route unreach panic): set skb->dev from skb_dst(skb)->dev before
    calling dst_link_failure().

    KASAN: null-ptr-deref in range [0x0000000000000328-0x000000000000032f]
    CPU: 1 PID: 12732 Comm: syz.1.3469 Not tainted 6.6.114 #2
    RIP: 0010:__in_dev_get_rcu include/linux/inetdevice.h:233
    RIP: 0010:fib_compute_spec_dst+0x17a/0x9f0 net/ipv4/fib_frontend.c:285
    Call Trace:
      <TASK>
      spec_dst_fill net/ipv4/ip_options.c:232
      spec_dst_fill net/ipv4/ip_options.c:229
      __ip_options_compile+0x13a1/0x17d0 net/ipv4/ip_options.c:330
      ipv4_send_dest_unreach net/ipv4/route.c:1252
      ipv4_link_failure+0x702/0xb80 net/ipv4/route.c:1265
      dst_link_failure include/net/dst.h:437
      __ip_vs_get_out_rt+0x15fd/0x19e0 net/netfilter/ipvs/ip_vs_xmit.c:412
      ip_vs_nat_xmit+0x1d8/0xc80 net/netfilter/ipvs/ip_vs_xmit.c:764

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-2026-053271
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?ebb556a5");
  # https://lore.kernel.org/linux-cve-announce/2026011312-CVE-2025-68813-13a5@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?fc946256");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2025-68813");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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-2025-68813");

  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:"2026/01/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/06");

  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 && 'loongarch64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'UOS Server', cpu);


var constraints = [
  {
    'release': '20',
    'sp': '1050a',
    'pkgs': [
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.132.24.uelc20', 'sp':'1050a', 'cpu':'loongarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.132.24.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_HOLE,
      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');
}