Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : libxml2 vulnerabilities (USN-8910-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8910-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(365375);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/13");

  script_cve_id(
    "CVE-2026-76781",
    "CVE-2026-86138",
    "CVE-2026-86139",
    "CVE-2026-86142",
    "CVE-2026-86143",
    "CVE-2026-86144"
  );
  script_xref(name:"IAVA", value:"2026-A-0980");
  script_xref(name:"USN", value:"8910-1");

  script_name(english:"Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : libxml2 vulnerabilities (USN-8910-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages
installed that are affected by multiple vulnerabilities as referenced in the USN-8910-1 advisory.

    Yirou Yang discovered that libxml2 incorrectly handled certain XML catalogs. If a user or automated system
    was tricked into processing a specially crafted XML catalog, an attacker could possibly use this issue to
    cause libxml2 to crash, resulting in a denial of service. (CVE-2026-76781)

    It was discovered that libxml2 incorrectly handled certain large qualified names, leading to a heap-based
    buffer overflow. An attacker could possibly use this issue to cause libxml2 to crash, resulting in a
    denial of service, or possibly execute arbitrary code. (CVE-2026-86138)

    It was discovered that libxml2 incorrectly handled escaping certain large URI strings. An attacker could
    possibly use this issue to cause libxml2 to use excessive resources, leading to a denial of service. This
    issue only affected Ubuntu 26.04 LTS. (CVE-2026-86139)

    Xudong Cao and Meng Xu discovered that libxml2 incorrectly handled certain large XPointer expressions,
    leading to a heap-based buffer overflow. An attacker could possibly use this issue to cause libxml2 to
    crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2026-86142)

    Xudong Cao and Meng Xu discovered that libxml2 did not check for integer overflows before passing output
    lengths to write callbacks. An attacker could possibly use this issue to cause an application using
    libxml2 to crash, resulting in a denial of service. (CVE-2026-86143)

    It was discovered that libxml2 did not apply parser options, such as disabling network access, when
    processing XInclude directives under certain circumstances. An attacker could possibly use this issue to
    perform XML external entity injection or server-side request forgery attacks, or cause a denial of
    service. (CVE-2026-86144)

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

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-8910-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  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:POC/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:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-86144");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/09/05");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/13");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:24.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libxml2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libxml2-16");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libxml2-source");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libxml2-utils");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python-libxml2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3-libxml2");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

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

  script_copyright(english:"Ubuntu Security Notice (C) 2026 Canonical, Inc. / NASL script (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('14.04' >< os_release || '16.04' >< os_release || '18.04' >< os_release || '20.04' >< os_release || '22.04' >< os_release || '24.04' >< os_release || '26.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 14.04 / 16.04 / 18.04 / 20.04 / 22.04 / 24.04 / 26.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);

var pkgs = [
    {'osver': '14.04', 'pkgname': 'libxml2', 'pkgver': '2.9.1+dfsg1-3ubuntu4.13+esm13', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '14.04', 'pkgname': 'libxml2-utils', 'pkgver': '2.9.1+dfsg1-3ubuntu4.13+esm13', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '14.04', 'pkgname': 'python-libxml2', 'pkgver': '2.9.1+dfsg1-3ubuntu4.13+esm13', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '16.04', 'pkgname': 'libxml2', 'pkgver': '2.9.3+dfsg1-1ubuntu0.7+esm14', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '16.04', 'pkgname': 'libxml2-utils', 'pkgver': '2.9.3+dfsg1-1ubuntu0.7+esm14', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '16.04', 'pkgname': 'python-libxml2', 'pkgver': '2.9.3+dfsg1-1ubuntu0.7+esm14', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '18.04', 'pkgname': 'libxml2', 'pkgver': '2.9.4+dfsg1-6.1ubuntu1.9+esm9', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '18.04', 'pkgname': 'libxml2-utils', 'pkgver': '2.9.4+dfsg1-6.1ubuntu1.9+esm9', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '18.04', 'pkgname': 'python-libxml2', 'pkgver': '2.9.4+dfsg1-6.1ubuntu1.9+esm9', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '18.04', 'pkgname': 'python3-libxml2', 'pkgver': '2.9.4+dfsg1-6.1ubuntu1.9+esm9', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '20.04', 'pkgname': 'libxml2', 'pkgver': '2.9.10+dfsg-5ubuntu0.20.04.10+esm6', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '20.04', 'pkgname': 'libxml2-utils', 'pkgver': '2.9.10+dfsg-5ubuntu0.20.04.10+esm6', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '20.04', 'pkgname': 'python-libxml2', 'pkgver': '2.9.10+dfsg-5ubuntu0.20.04.10+esm6', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '20.04', 'pkgname': 'python3-libxml2', 'pkgver': '2.9.10+dfsg-5ubuntu0.20.04.10+esm6', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '22.04', 'pkgname': 'libxml2', 'pkgver': '2.9.13+dfsg-1ubuntu0.14', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '22.04', 'pkgname': 'libxml2-utils', 'pkgver': '2.9.13+dfsg-1ubuntu0.14', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '22.04', 'pkgname': 'python3-libxml2', 'pkgver': '2.9.13+dfsg-1ubuntu0.14', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '24.04', 'pkgname': 'libxml2', 'pkgver': '2.9.14+dfsg-1.3ubuntu3.10', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '24.04', 'pkgname': 'libxml2-utils', 'pkgver': '2.9.14+dfsg-1.3ubuntu3.10', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '24.04', 'pkgname': 'python3-libxml2', 'pkgver': '2.9.14+dfsg-1.3ubuntu3.10', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '26.04', 'pkgname': 'libxml2-16', 'pkgver': '2.15.2+dfsg-0.1ubuntu0.3', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86139', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '26.04', 'pkgname': 'libxml2-source', 'pkgver': '2.15.2+dfsg-0.1ubuntu0.3', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86139', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '26.04', 'pkgname': 'libxml2-utils', 'pkgver': '2.15.2+dfsg-0.1ubuntu0.3', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86139', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']},
    {'osver': '26.04', 'pkgname': 'python3-libxml2', 'pkgver': '2.15.2+dfsg-0.1ubuntu0.3', 'cves': ['CVE-2026-76781', 'CVE-2026-86138', 'CVE-2026-86139', 'CVE-2026-86142', 'CVE-2026-86143', 'CVE-2026-86144']}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (osver && pkgname && pkgver) {
    if (deb_check(release:osver, prefix:pkgname, reference:pkgver, cves:cves)) flag++;
  }
}

if (flag)
{
  var extra = '';
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'libxml2 / libxml2-16 / libxml2-source / libxml2-utils / etc');
}