Amazon Linux 2023 : nginx, nginx-all-modules, nginx-core (ALAS2023-2026-1773)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2023 Security Advisory ALAS2023-2026-1773.
##

include('compat.inc');

if (description)
{
  script_id(319859);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/08");

  script_cve_id("CVE-2026-9256");
  script_xref(name:"IAVA", value:"2026-A-0515");

  script_name(english:"Amazon Linux 2023 : nginx, nginx-all-modules, nginx-core (ALAS2023-2026-1773)");

  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 a vulnerability as referenced in the ALAS2023-2026-1773 advisory.

    NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This
    vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-
    Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that
    references multiple such captures (for example, $1$2) in a redirect or arguments context. An
    unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by
    sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading
    to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization
    (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of
    Technical Support (EoTS) are not evaluated. (CVE-2026-9256)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue 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/ALAS2023-2026-1773.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-2026-9256.html");
  script_set_attribute(attribute:"solution", value:
"Run 'dnf update nginx --releasever 2023.12.20260608' or
  or 'dnf update --advisory ALAS2023-2026-1773 --releasever 2023.12.20260608' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/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:N/AC:H/PR:N/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:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:P");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-9256");

  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:"2026/05/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/06/08");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-all-modules");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-core-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-debugsource");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-filesystem");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-http-image-filter");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-http-image-filter-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-http-perl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-http-perl-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-http-xslt-filter");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-http-xslt-filter-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-mail");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-mail-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-stream");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:nginx-mod-stream-debuginfo");
  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':'nginx-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-all-modules-1.30.2-1.amzn2023.0.1', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-core-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-core-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-core-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-core-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-debugsource-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-debugsource-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-filesystem-1.30.2-1.amzn2023.0.1', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-devel-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-devel-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-image-filter-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-image-filter-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-image-filter-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-image-filter-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-perl-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-perl-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-perl-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-perl-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-xslt-filter-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-xslt-filter-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-xslt-filter-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-http-xslt-filter-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-mail-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-mail-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-mail-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-mail-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-stream-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-stream-1.30.2-1.amzn2023.0.1', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-stream-debuginfo-1.30.2-1.amzn2023.0.1', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'nginx-mod-stream-debuginfo-1.30.2-1.amzn2023.0.1', '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, "nginx / nginx-all-modules / nginx-core / etc");
}