Slackware Linux 15.0 / current libtasn1 Vulnerability (SSA:2026-008-01)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##
#
# The descriptive text and package checks in this plugin were
# extracted from Slackware Security Advisory SSA:2026-008-01. The text
# itself is copyright (C) Slackware Linux, Inc.
##

include('compat.inc');

if (description)
{
  script_id(282489);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/01/16");

  script_cve_id("CVE-2025-13151");
  script_xref(name:"IAVA", value:"2026-A-0027");

  script_name(english:"Slackware Linux 15.0 / current libtasn1  Vulnerability (SSA:2026-008-01)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Slackware Linux host is missing a security update to libtasn1.");
  script_set_attribute(attribute:"description", value:
"The version of libtasn1 installed on the remote host is prior to 4.21.0. It is, therefore, affected by a vulnerability
as referenced in the SSA:2026-008-01 advisory.

    New libtasn1 packages are available for Slackware 15.0 and -current to fix a security issue.

Tenable has extracted the preceding description block directly from the libtasn1 security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  # http://www.slackware.com/security/viewer.php?l=slackware-security&y=2026&m=slackware-security.342670
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?55892be2");
  script_set_attribute(attribute:"solution", value:
"Upgrade the affected libtasn1 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-2025-13151");

  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:"2026/01/07");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/01/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/01/09");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:slackware:slackware_linux:libtasn1");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:slackware:slackware_linux");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:slackware:slackware_linux:15.0");
  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:"Slackware 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_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/Slackware/release", "Host/Slackware/packages");

  exit(0);
}

include("slackware.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/Slackware/release")) audit(AUDIT_OS_NOT, "Slackware");
if (!get_kb_item("Host/Slackware/packages")) 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$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Slackware", cpu);

var flag = 0;
var constraints = [
    { 'fixed_version' : '4.21.0', 'product' : 'libtasn1', 'os_name' : 'Slackware Linux', 'os_version' : '15.0', 'service_pack' : '1_slack15.0', 'arch' : 'i586' },
    { 'fixed_version' : '4.21.0', 'product' : 'libtasn1', 'os_name' : 'Slackware Linux', 'os_version' : '15.0', 'service_pack' : '1_slack15.0', 'arch' : 'x86_64' },
    { 'fixed_version' : '4.21.0', 'product' : 'libtasn1', 'os_name' : 'Slackware Linux', 'os_version' : 'current', 'service_pack' : '1', 'arch' : 'i686' },
    { 'fixed_version' : '4.21.0', 'product' : 'libtasn1', 'os_name' : 'Slackware Linux', 'os_version' : 'current', 'service_pack' : '1', 'arch' : 'x86_64' }
];

foreach var constraint (constraints) {
    var pkg_arch = constraint['arch'];
    var arch = NULL;
    if (pkg_arch == "x86_64") {
        arch = pkg_arch;
    }
    if (slackware_check(osver:constraint['os_version'],
                        arch:arch,
                        pkgname:constraint['product'],
                        pkgver:constraint['fixed_version'],
                        pkgarch:pkg_arch,
                        pkgnum:constraint['service_pack'])) flag++;
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : slackware_report_get()
  );
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");