TencentOS Server 3: libxml2 (TSSA-2026:1213)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2026:1213.
##

include('compat.inc');

if (description)
{
  script_id(372233);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/27");

  script_cve_id(
    "CVE-2026-74860",
    "CVE-2026-86138",
    "CVE-2026-86140",
    "CVE-2026-86143",
    "CVE-2026-86144"
  );
  script_xref(name:"IAVA", value:"2026-A-0980");

  script_name(english:"TencentOS Server 3: libxml2 (TSSA-2026:1213)");

  script_set_attribute(attribute:"synopsis", value:
"The remote TencentOS Server 3 host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The version of Tencent Linux installed on the remote TencentOS Server 3 host is prior to tested version. It is,
therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:1213 advisory.

    Package updates are available for TencentOS Server 3 that fix the following vulnerabilities:

    CVE-2026-74860:
    A flaw was found in libxml2 with Python bindings enabled. A remote attacker could exploit this
    vulnerability by providing a specially crafted XML document containing a Document Type Definition (DTD)
    with enumerated attribute values. This triggers a double-free error in the SAX attributeDecl callback
    handler, where a string is freed twice. This flaw can lead to a denial of service (DoS) due to a
    reproducible crash in Python applications using the libxml2 SAX bindings.

    CVE-2026-86138:
    In libxml2 before 2.15.4, xmlDictAddQString in dict.c has an integer overflow and resultant heap-based
    buffer overflow.

    CVE-2026-86140:
    In libxml2 before 2.15.4, xmlSnprintfElements in valid.c has a strcat stack-based buffer overflow.

    CVE-2026-86143:
    In xmlIO in libxml2 before 2.15.4, an inconsistency in xmlOutputWriteCallback and xmlBufUse causes
    negative lengths to reach write callbacks, aka a lack of a check for integer overflow before calling
    writecallback. This has security relevance for many types of uses of that length value within a callback.

    CVE-2026-86144:
    In xinclude in libxml2 before 2.15.4, xmlXIncludeProcess and xmlXIncludeProcessTree do not propagate
    parseFlags. This has security relevance for, for example, the XML_PARSE_NONET flag, if (without it) a
    custom resource loader accesses the internet and triggers XML external entity injection, SSRF, or a denial
    of service (e.g., for an attacker-controlled internet resource that is intentionally slow).

Tenable has extracted the preceding description block directly from the Tencent Linux 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://mirrors.tencent.com/tlinux/errata/tssa-20261213.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/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:L/AC:L/PR:L/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-2026-86144");

  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:"2026/09/05");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/24");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/27");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:tencent:tencentos_server:3");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:tencent:tencentos_server:libxml2");
  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:"Tencent 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/local_checks_enabled", "Host/etc/os-release", "Host/TencentOS/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.inc');

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) || 'TencentOS' >!< os_product) audit(AUDIT_OS_NOT, 'TencentOS');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'TencentOS');
if (! preg(pattern:"^3([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'TencentOS 3.x', 'TencentOS ' + os_version);

if (!get_kb_item('Host/TencentOS/rpm-list')) 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, 'TencentOS', cpu);

var constraints = [
  {
    'release': '3',
    'pkgs': [
      {'reference':'libxml2-2.9.7-21.tl3.9', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libxml2-2.9.7-21.tl3.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libxml2-debuginfo-2.9.7-21.tl3.9', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libxml2-debuginfo-2.9.7-21.tl3.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libxml2-debugsource-2.9.7-21.tl3.9', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libxml2-debugsource-2.9.7-21.tl3.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libxml2-devel-2.9.7-21.tl3.9', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libxml2-devel-2.9.7-21.tl3.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-libxml2-2.9.7-21.tl3.9', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-libxml2-2.9.7-21.tl3.9', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-libxml2-debuginfo-2.9.7-21.tl3.9', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'python3-libxml2-debuginfo-2.9.7-21.tl3.9', 'cpu':'x86_64', '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_WARNING,
      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, 'libxml2 / libxml2-debuginfo / libxml2-debugsource / etc');
}