Amazon Linux 2 : libxml2, --advisory ALAS2-2026-3144 (ALAS-2026-3144)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALAS-2026-3144.
##

include('compat.inc');

if (description)
{
  script_id(298135);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/02/05");

  script_cve_id("CVE-2026-0990", "CVE-2026-0992");
  script_xref(name:"IAVA", value:"2025-A-0840");

  script_name(english:"Amazon Linux 2 : libxml2, --advisory ALAS2-2026-3144 (ALAS-2026-3144)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of libxml2 installed on the remote host is prior to 2.9.1-6. It is, therefore, affected by multiple
vulnerabilities as referenced in the ALAS2-2026-3144 advisory.

    A flaw was found in libxml2, an XML parsing library. This uncontrolled recursion vulnerability occurs in
    the xmlCatalogXMLResolveURI function when an XML catalog contains a delegate URI entry that references
    itself. A remote attacker could exploit this configuration-dependent issue by providing a specially
    crafted XML catalog, leading to infinite recursion and call stack exhaustion. This ultimately results in a
    segmentation fault, causing a Denial of Service (DoS) by crashing affected applications. (CVE-2026-0990)

    A flaw was found in the libxml2 library. This uncontrolled resource consumption vulnerability occurs when
    processing XML catalogs that contain repeated <nextCatalog> elements pointing to the same downstream
    catalog. A remote attacker can exploit this by supplying crafted catalogs, causing the parser to
    redundantly traverse catalog chains. This leads to excessive CPU consumption and degrades application
    availability, resulting in a denial-of-service condition. (CVE-2026-0992)

Tenable has extracted the preceding description block directly from the tested product 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://alas.aws.amazon.com//AL2/ALAS2-2026-3144.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-0990.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-0992.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update libxml2' or
  or 'yum update --advisory ALAS2-2026-3144' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/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:H/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-2026-0990");

  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:"2025/11/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/02/05");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/02/05");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libxml2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libxml2-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libxml2-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libxml2-python");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libxml2-static");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  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:"Amazon Linux 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/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}

include("rpm.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

var alas_release = get_kb_item("Host/AmazonLinux/release");
if (isnull(alas_release) || !strlen(alas_release)) audit(AUDIT_OS_NOT, "Amazon Linux");
var os_ver = pregmatch(pattern: "^AL(A|\d+|-\d+)", string:alas_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "2")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}

if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

var pkgs = [
    {'reference':'libxml2-2.9.1-6.amzn2.5.22', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-2.9.1-6.amzn2.5.22', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-2.9.1-6.amzn2.5.22', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-debuginfo-2.9.1-6.amzn2.5.22', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-debuginfo-2.9.1-6.amzn2.5.22', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-debuginfo-2.9.1-6.amzn2.5.22', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-devel-2.9.1-6.amzn2.5.22', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-devel-2.9.1-6.amzn2.5.22', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-devel-2.9.1-6.amzn2.5.22', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-python-2.9.1-6.amzn2.5.22', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-python-2.9.1-6.amzn2.5.22', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-python-2.9.1-6.amzn2.5.22', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-static-2.9.1-6.amzn2.5.22', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-static-2.9.1-6.amzn2.5.22', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-static-2.9.1-6.amzn2.5.22', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var _release = NULL;
  var sp = NULL;
  var _cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = NULL;
  var cves = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) _release = package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) _cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (reference && _release && (!exists_check || rpm_exists(release:_release, rpm:exists_check))) {
    if (rpm_check(release:_release, 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-devel / etc");
}