CentOS Linux 7 [TuxCare] Security Update: gnutls / gnutls-c++ / gnutls-dane / gnutls-devel / gnutls-utils Multiple Vulnerabilities (CENTOS7:CLSA-2026:1780925342)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(351685);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/30");

  script_cve_id(
    "CVE-2026-5260",
    "CVE-2026-33846",
    "CVE-2026-42009",
    "CVE-2026-42012",
    "CVE-2026-42013"
  );
  script_xref(name:"CLSA", value:"2026:1780925342");

  script_name(english:"CentOS Linux 7 [TuxCare] Security Update: gnutls / gnutls-c++ / gnutls-dane / gnutls-devel / gnutls-utils Multiple Vulnerabilities (CENTOS7:CLSA-2026:1780925342)");

  script_set_attribute(attribute:"synopsis", value:
"The CentOS Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The CentOS Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the
TuxCare CENTOS7:CLSA-2026:1780925342 advisory.

  - A heap buffer overflow vulnerability exists in the DTLS handshake fragment reassembly logic of GnuTLS. The
    issue arises in merge_handshake_packet() where incoming handshake fragments are matched and merged based
    solely on handshake type, without validating that the message_length field remains consistent across all
    fragments of the same logical message. An attacker can exploit this by sending crafted DTLS fragments with
    conflicting message_length values, causing the implementation to allocate a buffer based on a smaller
    initial fragment and subsequently write beyond its bounds using larger, inconsistent fragments. Because
    the merge operation does not enforce proper bounds checking against the allocated buffer size, this
    results in an out-of-bounds write on the heap. The vulnerability is remotely exploitable without
    authentication via the DTLS handshake path and can lead to application crashes or potential memory
    corruption. (CVE-2026-33846)

  - A flaw was found in gnutls. A remote attacker could exploit an issue in the Datagram Transport Layer
    Security (DTLS) packet reordering logic. The comparator function, responsible for ordering DTLS packets by
    sequence numbers, did not correctly handle packets with duplicate sequence numbers. This could lead to
    unstable packet ordering or undefined behavior, resulting in a denial of service. (CVE-2026-42009)

  - A flaw was found in gnutls. A remote attacker could exploit this vulnerability by presenting a specially
    crafted certificate that contains Uniform Resource Identifier (URI) or Service (SRV) Subject Alternative
    Names (SANs). This could cause the certificate validation process to incorrectly fall back to checking DNS
    hostnames against the Common Name (CN), potentially allowing the attacker to spoof legitimate services or
    intercept sensitive information. (CVE-2026-42012)

  - A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN)
    could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This
    could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or
    man-in-the-middle attacks. (CVE-2026-42013)

  - A flaw was found in libgnutls. A remote attacker, by sending an extremely short premaster secret during an
    RSA key exchange to a server using an RSA key backed by a PKCS#11 token, could trigger a short heap
    overread. This memory corruption vulnerability could lead to information disclosure. (CVE-2026-5260)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://security.tuxcare.com/csaf/v2/els_os/centos7els/advisories/2026/clsa-2026_1780925342.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?197b24e3");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1780925342");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory CENTOS7:CLSA-2026:1780925342.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/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:L/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-2026-5260");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_severity", value:"Important");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/04/30");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/30");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"CentOS 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_info2.nasl");
  script_require_keys("Host/OS/extended-third-party", "Host/local_checks_enabled", "Host/CentOS/release", "Host/CentOS/rpm-list");

  exit(0);
}
include('rpm2.inc');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (empty_or_null(third_party_support) || third_party_support != 'TuxCare') exit(0, 'TuxCare support not enabled.');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'CentOS Linux' >!< os_product) audit(AUDIT_OS_NOT, 'CentOS Linux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'CentOS Linux');
if (! preg(pattern:"^7([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'CentOS Linux 7', 'CentOS Linux ' + os_version);

if (!get_kb_item('Host/CentOS/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

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


var constraints = [
  {
    'release': '7',
    'pkgs': [
      {'reference':'gnutls-3.3.29-9.el7_9.tuxcare.els5', 'cpu':'i686', 'el_string':'el7_9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'gnutls-3.3.29-9.el7_9.tuxcare.els5', 'cpu':'x86_64', 'el_string':'el7_9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'gnutls-c++-3.3.29-9.el7_9.tuxcare.els5', 'cpu':'i686', 'el_string':'el7_9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'gnutls-c++-3.3.29-9.el7_9.tuxcare.els5', 'cpu':'x86_64', 'el_string':'el7_9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'gnutls-dane-3.3.29-9.el7_9.tuxcare.els5', 'cpu':'i686', 'el_string':'el7_9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'gnutls-dane-3.3.29-9.el7_9.tuxcare.els5', 'cpu':'x86_64', 'el_string':'el7_9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'gnutls-devel-3.3.29-9.el7_9.tuxcare.els5', 'cpu':'i686', 'el_string':'el7_9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'gnutls-devel-3.3.29-9.el7_9.tuxcare.els5', 'cpu':'x86_64', 'el_string':'el7_9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'gnutls-utils-3.3.29-9.el7_9.tuxcare.els5', 'cpu':'x86_64', 'el_string':'el7_9', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}


if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'gnutls / gnutls-c++ / gnutls-dane / gnutls-devel / gnutls-utils');
}