Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : GnuTLS vulnerabilities (USN-8539-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8539-1. 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(327062);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/15");

  script_cve_id(
    "CVE-2026-42011",
    "CVE-2026-42012",
    "CVE-2026-42013",
    "CVE-2026-42014",
    "CVE-2026-42015"
  );
  script_xref(name:"USN", value:"8539-1");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : GnuTLS vulnerabilities (USN-8539-1)");

  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 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple
vulnerabilities as referenced in the USN-8539-1 advisory.

    Haruto Kimura discovered that GnuTLS did not properly apply permitted name constraints in certain
    certificate validation paths. A remote attacker could possibly use this issue to bypass certificate
    validation, leading to a machine-in-the-middle attack. (CVE-2026-42011)

    Oleh Konko discovered that GnuTLS incorrectly fell back to Common Name checks for certain URI and SRV
    subject alternative names. A remote attacker could possibly use this issue to bypass certificate
    validation, leading to a machine-in-the-middle attack. (CVE-2026-42012)

    Haruto Kimura and Joshua Rogers discovered that GnuTLS incorrectly fell back to Common Name checks when
    subject alternative names were oversized. A remote attacker could possibly use this issue to bypass
    certificate validation, leading to a machine-in-the-middle attack. (CVE-2026-42013)

    Luigino Camastra and Joshua Rogers discovered that GnuTLS had a use-after-free issue when changing PKCS#11
    token security officer PINs in certain cases. An attacker could possibly use this issue to cause GnuTLS to
    crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-42014)

    Zou Dikai discovered that GnuTLS did not properly validate PKCS#12 bag sizes in certain cases. An attacker
    could possibly use this issue to cause GnuTLS to crash, resulting in a denial of service, or execute
    arbitrary code. (CVE-2026-42015)

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-8539-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:C/A:N");
  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:L/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-42013");

  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:"2026/04/30");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/14");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/15");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:"p-cpe:/a:canonical:ubuntu_linux:gnutls-bin");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:guile-gnutls");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libgnutls-dane0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libgnutls-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libgnutls-openssl27");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libgnutls28-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libgnutls30");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libgnutlsxx28");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  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_info.nasl", "ubuntu_pro_sub_detect.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 (! ('16.04' >< os_release || '18.04' >< os_release || '20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 16.04 / 18.04 / 20.04', '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 ubuntu_pro_detected = get_kb_item('Host/Ubuntu/Pro/Services/esm-apps');
ubuntu_pro_detected = !empty_or_null(ubuntu_pro_detected);

var pro_caveat_needed = FALSE;

var pkgs = [
    {'osver': '16.04', 'pkgname': 'gnutls-bin', 'pkgver': '3.4.10-4ubuntu1.9+esm4', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'guile-gnutls', 'pkgver': '3.4.10-4ubuntu1.9+esm4', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'libgnutls-dev', 'pkgver': '3.4.10-4ubuntu1.9+esm4', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'libgnutls-openssl27', 'pkgver': '3.4.10-4ubuntu1.9+esm4', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'libgnutls28-dev', 'pkgver': '3.4.10-4ubuntu1.9+esm4', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'libgnutls30', 'pkgver': '3.4.10-4ubuntu1.9+esm4', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'libgnutlsxx28', 'pkgver': '3.4.10-4ubuntu1.9+esm4', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'gnutls-bin', 'pkgver': '3.5.18-1ubuntu1.6+esm4', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'libgnutls-dane0', 'pkgver': '3.5.18-1ubuntu1.6+esm4', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'libgnutls-openssl27', 'pkgver': '3.5.18-1ubuntu1.6+esm4', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'libgnutls28-dev', 'pkgver': '3.5.18-1ubuntu1.6+esm4', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'libgnutls30', 'pkgver': '3.5.18-1ubuntu1.6+esm4', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'libgnutlsxx28', 'pkgver': '3.5.18-1ubuntu1.6+esm4', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'gnutls-bin', 'pkgver': '3.6.13-2ubuntu1.12+esm3', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'guile-gnutls', 'pkgver': '3.6.13-2ubuntu1.12+esm3', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'libgnutls-dane0', 'pkgver': '3.6.13-2ubuntu1.12+esm3', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'libgnutls-openssl27', 'pkgver': '3.6.13-2ubuntu1.12+esm3', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'libgnutls28-dev', 'pkgver': '3.6.13-2ubuntu1.12+esm3', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'libgnutls30', 'pkgver': '3.6.13-2ubuntu1.12+esm3', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'libgnutlsxx28', 'pkgver': '3.6.13-2ubuntu1.12+esm3', 'ubuntu_pro': TRUE}
];

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

if (flag)
{
  var extra = '';
  if (pro_caveat_needed) {
    extra += 'NOTE: This vulnerability check contains fixes that apply to packages only \n';
    extra += 'available in Ubuntu ESM repositories. Access to these package security updates \n';
    extra += 'require an Ubuntu Pro subscription.\n\n';
  }
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    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, 'gnutls-bin / guile-gnutls / libgnutls-dane0 / libgnutls-dev / etc');
}