Amazon Linux 2023 : rpcbind (ALAS2023-2026-3169)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2023 Security Advisory ALAS2023-2026-3169.
##

include('compat.inc');

if (description)
{
  script_id(365181);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/12");

  script_cve_id("CVE-2026-16277", "CVE-2026-16461", "CVE-2026-94640");

  script_name(english:"Amazon Linux 2023 : rpcbind (ALAS2023-2026-3169)");

  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 ALAS2023-2026-3169 advisory.

    A stack-based buffer overflow was found in rpcbind's rpcinfo utility. When querying a remote rpcbind
    service with `rpcinfo -l`, address information returned by the server is copied into a fixed-size buffer
    without sufficient bounds checking. A malicious or compromised rpcbind server could use this flaw to crash
    the rpcinfo client, resulting in a denial of service. The highest threat from this vulnerability is to
    system availability. (CVE-2026-16277)

    A stack-based buffer overflow was found in rpcbind's rpcinfo utility. In rpcbdump() short mode (used by
    `rpcinfo -s`), version numbers from a remote RPCBPROC_DUMP reply are written into a fixed-size stack
    buffer without bounds checking. A user or administrator who runs `rpcinfo -s` against a malicious or
    compromised rpcbind endpoint could experience a crash or denial of service of the rpcinfo client.
    (CVE-2026-16461)

    A flaw was found in rpcbind. This vulnerability allows a remote, unauthenticated attacker to cause a
    Denial of Service (DoS) by sending a large number of unique requests. The rpcbind service records
    previously unseen RPC (Remote Procedure Call) statistics in unbounded in-memory lists, leading to
    persistent memory growth and increased CPU usage. This can degrade or exhaust service availability.
    (CVE-2026-94640)

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/ALAS2023-2026-3169.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-2026-16277.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-16461.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-94640.html");
  script_set_attribute(attribute:"solution", value:
"Run 'dnf update rpcbind --releasever 2023.12.20261012' or
  or 'dnf update --advisory ALAS2023-2026-3169 --releasever 2023.12.20261012' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/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:L/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-2026-94640");

  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:"2026/07/20");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/12");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:rpcbind");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:rpcbind-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:rpcbind-debugsource");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2023");
  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_info2.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 != "-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':'rpcbind-1.2.6-0.amzn2023.0.3', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'rpcbind-1.2.6-0.amzn2023.0.3', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'rpcbind-debuginfo-1.2.6-0.amzn2023.0.3', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'rpcbind-debuginfo-1.2.6-0.amzn2023.0.3', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'rpcbind-debugsource-1.2.6-0.amzn2023.0.3', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'rpcbind-debugsource-1.2.6-0.amzn2023.0.3', '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, "rpcbind / rpcbind-debuginfo / rpcbind-debugsource");
}