Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : GnuTLS vulnerabilities (USN-8502-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8502-1. 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(325430);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/07");

  script_cve_id(
    "CVE-2024-0553",
    "CVE-2024-12243",
    "CVE-2025-9820",
    "CVE-2025-14831",
    "CVE-2026-3833",
    "CVE-2026-5260",
    "CVE-2026-33845",
    "CVE-2026-33846",
    "CVE-2026-42009",
    "CVE-2026-42010"
  );
  script_xref(name:"USN", value:"8502-1");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : GnuTLS vulnerabilities (USN-8502-1)");

  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-8502-1 advisory.

    It was discovered that GnuTLS had a timing side-channel when processing malformed ciphertexts in RSA-PSK
    ClientKeyExchange. A remote attacker could possibly use this issue to recover sensitive information. This
    issue only affected Ubuntu 18.04 LTS. (CVE-2024-0553)

    Bing Shi discovered that GnuTLS incorrectly handled decoding certain DER-encoded certificates. A remote
    attacker could possibly use this issue to cause GnuTLS to consume resources, leading to a denial of
    service. This issue only affected Ubuntu 18.04 LTS. (CVE-2024-12243)

    Luigino Camastra discovered that GnuTLS incorrectly handled certain PKCS11 token labels. A remote attacker
    could use this issue to cause GnuTLS to crash, resulting in a denial of service, or possibly execute
    arbitrary code. The default compiler options for affected releases should reduce the vulnerability to a
    denial of service. (CVE-2025-9820)

    Tim Scheckenbach discovered that GnuTLS incorrectly handled malicious certificates containing a large
    number of name constraints and subject alternative names. A remote attacker could possibly use this issue
    to cause GnuTLS to consume resources, resulting in a denial of service. This issue only affected Ubuntu
    18.04 LTS and Ubuntu 20.04 LTS. (CVE-2025-14831)

    Oleh Konko and Joshua Rogers discovered that GnuTLS did not properly handle case-insensitive name
    constraints in certain cases. A remote attacker could possibly use this issue to bypass certificate
    validation, leading to a machine-in-the-middle attack. (CVE-2026-3833)

    Joshua Rogers discovered that GnuTLS did not properly handle very short premaster secrets in certain RSA
    key exchange cases with PKCS#11-backed server keys. A remote attacker could possibly use this issue to
    obtain sensitive information. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS.
    (CVE-2026-5260)

    Joshua Rogers discovered that GnuTLS did not properly handle malformed DTLS handshake fragments in certain
    cases. A remote attacker could possibly use this issue to obtain sensitive information, or cause a denial
    of service. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-33845)

    Haruto Kimura, Oscar Reparaz, and Zou Dikai discovered that GnuTLS did not properly validate DTLS
    handshake fragment lengths in certain cases. A remote attacker could possibly use this issue to cause
    GnuTLS to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-33846)

    Joshua Rogers discovered that GnuTLS did not properly order DTLS packets with duplicate sequence numbers
    in certain cases. A remote attacker could possibly use this issue to cause GnuTLS to crash, resulting in a
    denial of service. (CVE-2026-42009)

    Joshua Rogers discovered that GnuTLS did not properly handle usernames containing NUL characters in
    certain RSA-PSK configurations. A remote attacker could possibly use this issue to bypass authentication
    and gain unintended access to services. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-42010)

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-8502-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/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:N/AC:L/PR:N/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-2026-42010");

  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:"2023/06/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/06");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/07");

  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+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2026-3833', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '16.04', 'pkgname': 'guile-gnutls', 'pkgver': '3.4.10-4ubuntu1.9+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2026-3833', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '16.04', 'pkgname': 'libgnutls-dev', 'pkgver': '3.4.10-4ubuntu1.9+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2026-3833', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '16.04', 'pkgname': 'libgnutls-openssl27', 'pkgver': '3.4.10-4ubuntu1.9+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2026-3833', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '16.04', 'pkgname': 'libgnutls28-dev', 'pkgver': '3.4.10-4ubuntu1.9+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2026-3833', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '16.04', 'pkgname': 'libgnutls30', 'pkgver': '3.4.10-4ubuntu1.9+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2026-3833', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '16.04', 'pkgname': 'libgnutlsxx28', 'pkgver': '3.4.10-4ubuntu1.9+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2026-3833', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '18.04', 'pkgname': 'gnutls-bin', 'pkgver': '3.5.18-1ubuntu1.6+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2024-0553', 'CVE-2024-12243', 'CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '18.04', 'pkgname': 'libgnutls-dane0', 'pkgver': '3.5.18-1ubuntu1.6+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2024-0553', 'CVE-2024-12243', 'CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '18.04', 'pkgname': 'libgnutls-openssl27', 'pkgver': '3.5.18-1ubuntu1.6+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2024-0553', 'CVE-2024-12243', 'CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '18.04', 'pkgname': 'libgnutls28-dev', 'pkgver': '3.5.18-1ubuntu1.6+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2024-0553', 'CVE-2024-12243', 'CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '18.04', 'pkgname': 'libgnutls30', 'pkgver': '3.5.18-1ubuntu1.6+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2024-0553', 'CVE-2024-12243', 'CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '18.04', 'pkgname': 'libgnutlsxx28', 'pkgver': '3.5.18-1ubuntu1.6+esm3', 'ubuntu_pro': TRUE, 'cves': ['CVE-2024-0553', 'CVE-2024-12243', 'CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33846', 'CVE-2026-42009']},
    {'osver': '20.04', 'pkgname': 'gnutls-bin', 'pkgver': '3.6.13-2ubuntu1.12+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33845', 'CVE-2026-33846', 'CVE-2026-42009', 'CVE-2026-42010']},
    {'osver': '20.04', 'pkgname': 'guile-gnutls', 'pkgver': '3.6.13-2ubuntu1.12+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33845', 'CVE-2026-33846', 'CVE-2026-42009', 'CVE-2026-42010']},
    {'osver': '20.04', 'pkgname': 'libgnutls-dane0', 'pkgver': '3.6.13-2ubuntu1.12+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33845', 'CVE-2026-33846', 'CVE-2026-42009', 'CVE-2026-42010']},
    {'osver': '20.04', 'pkgname': 'libgnutls-openssl27', 'pkgver': '3.6.13-2ubuntu1.12+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33845', 'CVE-2026-33846', 'CVE-2026-42009', 'CVE-2026-42010']},
    {'osver': '20.04', 'pkgname': 'libgnutls28-dev', 'pkgver': '3.6.13-2ubuntu1.12+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33845', 'CVE-2026-33846', 'CVE-2026-42009', 'CVE-2026-42010']},
    {'osver': '20.04', 'pkgname': 'libgnutls30', 'pkgver': '3.6.13-2ubuntu1.12+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33845', 'CVE-2026-33846', 'CVE-2026-42009', 'CVE-2026-42010']},
    {'osver': '20.04', 'pkgname': 'libgnutlsxx28', 'pkgver': '3.6.13-2ubuntu1.12+esm2', 'ubuntu_pro': TRUE, 'cves': ['CVE-2025-9820', 'CVE-2025-14831', 'CVE-2026-3833', 'CVE-2026-5260', 'CVE-2026-33845', 'CVE-2026-33846', 'CVE-2026-42009', 'CVE-2026-42010']}
];

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');
}