Ubuntu 22.04 LTS / 24.04 LTS / 25.04 / 25.10 : Libtasn1 vulnerabilities (USN-7954-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-7954-1. 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(284657);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/01/16");

  script_cve_id("CVE-2021-46848", "CVE-2025-13151");
  script_xref(name:"USN", value:"7954-1");
  script_xref(name:"IAVA", value:"2026-A-0027");

  script_name(english:"Ubuntu 22.04 LTS / 24.04 LTS / 25.04 / 25.10 : Libtasn1 vulnerabilities (USN-7954-1)");

  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 22.04 LTS / 24.04 LTS / 25.04 / 25.10 host has packages installed that are affected by multiple
vulnerabilities as referenced in the USN-7954-1 advisory.

    It was discovered that Libtasn1 incorrectly handled decoding ASN.1 content. An attacker could possibly use
    this issue to cause Libtasn1 to crash, resulting in a denial of service. (CVE-2025-13151)

    It was discovered that Libtasn1 incorrectly handled encoding ASN.1 content. An attacker could possibly use
    this issue to cause Libtasn1 to crash, resulting in a denial of service. This issue only affected Ubuntu
    22.04 LTS. (CVE-2021-46848)

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-7954-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected libtasn1-6, libtasn1-6-dev and / or libtasn1-bin packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:N/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:N/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-2021-46848");

  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:"2022/10/24");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/01/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/01/14");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:25.04");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:25.10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libtasn1-6");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libtasn1-6-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libtasn1-bin");
  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_info.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 (! ('22.04' >< os_release || '24.04' >< os_release || '25.04' >< os_release || '25.10' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 22.04 / 24.04 / 25.04 / 25.10', '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': '22.04', 'pkgname': 'libtasn1-6', 'pkgver': '4.18.0-4ubuntu0.2', 'cves': ['CVE-2021-46848', 'CVE-2025-13151']},
    {'osver': '22.04', 'pkgname': 'libtasn1-6-dev', 'pkgver': '4.18.0-4ubuntu0.2', 'cves': ['CVE-2021-46848', 'CVE-2025-13151']},
    {'osver': '22.04', 'pkgname': 'libtasn1-bin', 'pkgver': '4.18.0-4ubuntu0.2', 'cves': ['CVE-2021-46848', 'CVE-2025-13151']},
    {'osver': '24.04', 'pkgname': 'libtasn1-6', 'pkgver': '4.19.0-3ubuntu0.24.04.2', 'cves': ['CVE-2025-13151']},
    {'osver': '24.04', 'pkgname': 'libtasn1-6-dev', 'pkgver': '4.19.0-3ubuntu0.24.04.2', 'cves': ['CVE-2025-13151']},
    {'osver': '24.04', 'pkgname': 'libtasn1-bin', 'pkgver': '4.19.0-3ubuntu0.24.04.2', 'cves': ['CVE-2025-13151']},
    {'osver': '25.04', 'pkgname': 'libtasn1-6', 'pkgver': '4.20.0-2ubuntu0.25.04.1', 'cves': ['CVE-2025-13151']},
    {'osver': '25.04', 'pkgname': 'libtasn1-6-dev', 'pkgver': '4.20.0-2ubuntu0.25.04.1', 'cves': ['CVE-2025-13151']},
    {'osver': '25.04', 'pkgname': 'libtasn1-bin', 'pkgver': '4.20.0-2ubuntu0.25.04.1', 'cves': ['CVE-2025-13151']},
    {'osver': '25.10', 'pkgname': 'libtasn1-6', 'pkgver': '4.20.0-2ubuntu0.25.10.1', 'cves': ['CVE-2025-13151']},
    {'osver': '25.10', 'pkgname': 'libtasn1-6-dev', 'pkgver': '4.20.0-2ubuntu0.25.10.1', 'cves': ['CVE-2025-13151']},
    {'osver': '25.10', 'pkgname': 'libtasn1-bin', 'pkgver': '4.20.0-2ubuntu0.25.10.1', 'cves': ['CVE-2025-13151']}
];

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_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, 'libtasn1-6 / libtasn1-6-dev / libtasn1-bin');
}