Amazon Linux 2 : ecs-service-connect-agent (ALASECS-2026-137)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALASECS-2026-137.
##

include('compat.inc');

if (description)
{
  script_id(345786);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/14");

  script_cve_id(
    "CVE-2026-48521",
    "CVE-2026-50572",
    "CVE-2026-73511",
    "CVE-2026-73512",
    "CVE-2026-73513",
    "CVE-2026-73546",
    "CVE-2026-73547",
    "CVE-2026-73548",
    "CVE-2026-73549",
    "CVE-2026-73550",
    "CVE-2026-73551",
    "CVE-2026-73552",
    "CVE-2026-73553"
  );

  script_name(english:"Amazon Linux 2 : ecs-service-connect-agent (ALASECS-2026-137)");

  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 ecs-service-connect-agent installed on the remote host is prior to v1.39.1.0-1. It is, therefore,
affected by multiple vulnerabilities as referenced in the ALAS2ECS-2026-137 advisory.

    An Envoy proxy handling HTTP/3 connections can dereference a null transport socket option during the
    selection of a connection pool. This null pointer dereference is a CWE-476 flaw that may cause the process
    to crash or terminate unexpectedly, leading to a denial of service for the services routed through the
    affected Envoy instance. The vulnerability is triggered when a client initiates an HTTP/3 session that
    exercises the connection-pool selection logic, which may provide the attacker a remote execution path to
    disrupt the proxy. (CVE-2026-48521)

    Fixed a use-after-free in the ext_authz raw HTTP client where completing an authorization request could
    destroy the client while its completion handler was still executing. (CVE-2026-50572)

    Fixed path matching for paths containing per-segment parameters, where Envoy and backends could select
    different resources for the same request and bypass path-based selection or authentication.
    (CVE-2026-73511)

    Fixed a use-after-free in the QUIC HTTP datagram handler where late HTTP/3 datagrams could reference a
    stream decoder that was already destroyed or replaced. (CVE-2026-73512)

    Fixed a heap use-after-free where an untrusted upstream could send HTTP/2 response trailers without the
    END_STREAM flag to an Envoy instance using oghttp2, corrupting stream state and terminating the process.
    (CVE-2026-73513)

    Fixed a stored cross-site scripting issue in the HTML stats interface (/stats?format=html) where
    dynamically named statistics could introduce attacker-controlled content. (CVE-2026-73546)

    Fixed an abnormal process termination in the ext_authz filter when processing CONNECT requests without a
    :path pseudo-header. (CVE-2026-73547)

    Fixed cross-user response poisoning involving generic, non-WebSocket HTTP upgrades, where request payload
    sent before an upgrade was accepted could contaminate a shared upstream connection. (CVE-2026-73548)

    Fixed an abnormal process termination for scoped IPv6 client addresses in original DST clusters with
    HTTP/3. (CVE-2026-73549)

    Fixed an HTTP/2 memory-exhaustion issue where discarded duplicate Host headers were not counted toward
    request-header size and count limits. (CVE-2026-73550)

    Fixed URL normalization of dot and dot-dot path segments containing parameters, which could cause access-
    control components and upstream applications to interpret a request path differently. (CVE-2026-73551)

    Fixed an issue where safe_regex matching treated accepted non-UTF-8 HTTP header bytes as a non-match; in
    RBAC policies using negative matching this could fail open and allow access to a protected resource.
    (CVE-2026-73552)

    Fixed an authorization bypass when ignore_path_parameters_in_path_matching was enabled, where a path such
    as /admin;x could bypass an RBAC policy for /admin while still reaching the protected route.
    (CVE-2026-73553)

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/ALAS2ECS-2026-137.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-2026-48521.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-50572.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73511.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73512.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73513.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73546.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73547.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73548.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73549.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73550.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73551.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73552.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-73553.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update ecs-service-connect-agent' or
  or 'yum update --advisory ALAS2ECS-2026-137' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:N/I:N/A:P");
  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:C/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-2026-73553");

  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:"2026/09/14");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/14");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/14");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:ecs-service-connect-agent");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  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("rpm2.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 REPOS_FOUND = TRUE;
var extras_list = get_kb_item("Host/AmazonLinux/extras_label_list");
if (isnull(extras_list)) REPOS_FOUND = FALSE;
var repository = '"amzn2extra-ecs"';
if (REPOS_FOUND && (repository >!< extras_list)) exit(0, AFFECTED_REPO_NOT_ENABLED);

var pkgs = [
    {'reference':'ecs-service-connect-agent-v1.39.1.0-1.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'ecs-service-connect-agent-v1.39.1.0-1.amzn2', '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)
{
  var extra = rpm_report_get();
  if (!REPOS_FOUND) extra = rpm_report_get() + report_repo_caveat();
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : extra
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "ecs-service-connect-agent");
}