Amazon Linux 2023 : amazon-cloudwatch-agent (ALAS2023-2026-1572)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2023 Security Advisory ALAS2023-2026-1572.
##

include('compat.inc');

if (description)
{
  script_id(306228);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/04/13");

  script_cve_id(
    "CVE-2026-25679",
    "CVE-2026-27139",
    "CVE-2026-27142",
    "CVE-2026-33186"
  );
  script_xref(name:"IAVB", value:"2026-B-0055-S");

  script_name(english:"Amazon Linux 2023 : amazon-cloudwatch-agent (ALAS2023-2026-1572)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2023 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1572 advisory.

    url.Parse insufficiently validated the host/authority component and accepted some invalid URLs.
    (CVE-2026-25679)

    On Unix platforms, when listing the contents of a directory using File.ReadDir or File.Readdir the
    returned FileInfo could reference a file outside of the Root in which the File was opened. The impact of
    this escape is limited to reading metadata provided by lstat from arbitrary locations on the filesystem
    without permitting reading or writing files outside the root. (CVE-2026-27139)

    Actions which insert URLs into the content attribute of HTML meta tags are not escaped. This can allow XSS
    if the meta tag also has an http-equiv attribute with the value refresh. A new GODEBUG setting has been
    added, htmlmetacontenturlescape, which can be used to disable escaping URLs in actions in the meta content
    attribute which follow url= by setting htmlmetacontenturlescape=0. (CVE-2026-27142)

    gRPC-Go is the Go language implementation of gRPC. Versions prior to 1.79.3 have an authorization bypass
    resulting from improper input validation of the HTTP/2 `:path` pseudo-header. The gRPC-Go server was too
    lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash
    (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests
    to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated
    the raw, non-canonical path string. Consequently, deny rules defined using canonical paths (starting
    with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback allow
    rule was present. This affects gRPC-Go servers that use path-based authorization interceptors, such as the
    official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on
    `info.FullMethod` or `grpc.Method(ctx)`; AND that have a security policy contains specific deny rules
    for canonical paths but allows other requests by default (a fallback allow rule). The vulnerability is
    exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the
    gRPC server. The fix in version 1.79.3 ensures that any request with a `:path` that does not start with a
    leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching
    authorization interceptors or handlers with a non-canonical path string. While upgrading is the most
    secure and recommended path, users can mitigate the vulnerability using one of the following methods: Use
    a validating interceptor (recommended mitigation); infrastructure-level normalization; and/or policy
    hardening. (CVE-2026-33186)

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//AL2023/ALAS2023-2026-1572.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-2026-25679.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-27139.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-27142.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-33186.html");
  script_set_attribute(attribute:"solution", value:
"Run 'dnf update amazon-cloudwatch-agent --releasever 2023.11.20260413' or
  or 'dnf update --advisory ALAS2023-2026-1572 --releasever 2023.11.20260413' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N");
  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:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-33186");

  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:"2026/03/05");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/04/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/04/13");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:amazon-cloudwatch-agent");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2023");
  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 != "-2023")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2023", "Amazon Linux " + os_ver);
}

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

var pkgs = [
    {'reference':'amazon-cloudwatch-agent-1.300064.2-1.amzn2023', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'amazon-cloudwatch-agent-1.300064.2-1.amzn2023', 'cpu':'x86_64', 'release':'AL-2023', '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_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, "amazon-cloudwatch-agent");
}