RHEL 9 : nginx (RHSA-2026:93467)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Red Hat Security Advisory RHSA-2026:93467. The text
# itself is copyright (C) Red Hat, Inc.
##

include('compat.inc');

if (description)
{
  script_id(374923);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/11/02");

  script_cve_id(
    "CVE-2026-9256",
    "CVE-2026-42055",
    "CVE-2026-42533",
    "CVE-2026-56434",
    "CVE-2026-60005"
  );
  script_xref(name:"RHSA", value:"2026:93467");

  script_name(english:"RHEL 9 : nginx (RHSA-2026:93467)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Red Hat host is missing one or more security updates for nginx.");
  script_set_attribute(attribute:"description", value:
"The remote Redhat Enterprise Linux 9 host has packages installed that are affected by multiple vulnerabilities as
referenced in the RHSA-2026:93467 advisory.

    nginx is a web and proxy server supporting HTTP and other protocols, with a focus on high concurrency,
    performance, and low memory usage.

    Security Fix(es):

    * nginx: ngx_http_rewrite_module: code execution and denial of service (CVE-2026-9256)

    * nginx: NGINX: Arbitrary code execution or Denial of Service via heap-based buffer overflow with crafted
    HTTP/2 headers (CVE-2026-42055)

    * nginx: NGINX: Heap buffer over-read allows memory modification or denial of service (CVE-2026-56434)

    * nginx: NGINX: Arbitrary code execution via crafted HTTP requests (CVE-2026-42533)

    * nginx: NGINX: Memory disclosure and denial of service in ngx_http_slice_module (CVE-2026-60005)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and
    other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux 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://access.redhat.com/security/updates/classification/#important");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=2480746");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=2489866");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=2500960");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=2500967");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=2500992");
  # https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_93467.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?3fb2c684");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/errata/RHSA-2026:93467");
  script_set_attribute(attribute:"solution", value:
"Update the RHEL nginx package based on the guidance in RHSA-2026:93467.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:F/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:F/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-2026-60005");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-9256");
  script_set_attribute(attribute:"cvss4_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_cwe_id(122, 125, 131, 824);
  script_set_attribute(attribute:"vendor_severity", value:"Important");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/05/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/11/02");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/11/02");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:rhel_eus:9.6");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-all-modules");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-filesystem");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-http-image-filter");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-http-perl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-http-xslt-filter");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-mail");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nginx-mod-stream");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Red Hat 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", "redhat_repos.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.inc');
include('rhel.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'Red Hat' >!< os_product) audit(AUDIT_OS_NOT, 'Red Hat');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'Red Hat');
if (!rhel_check_release(operator: 'eq', os_version: os_version, rhel_version: '9.6')) audit(AUDIT_OS_NOT, 'Red Hat 9.6', 'Red Hat ' + os_version);

if (!get_kb_item('Host/RedHat/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu && 'ppc' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Red Hat', cpu);

var constraints = [
  {
    'release': '9',
    'sp': '6',
    'repo_relative_urls': [
      'content/aus/rhel9/9.6/x86_64/appstream/debug',
      'content/aus/rhel9/9.6/x86_64/appstream/os',
      'content/aus/rhel9/9.6/x86_64/appstream/source/SRPMS',
      'content/e4s/rhel9/9.6/aarch64/appstream/debug',
      'content/e4s/rhel9/9.6/aarch64/appstream/os',
      'content/e4s/rhel9/9.6/aarch64/appstream/source/SRPMS',
      'content/e4s/rhel9/9.6/ppc64le/appstream/debug',
      'content/e4s/rhel9/9.6/ppc64le/appstream/os',
      'content/e4s/rhel9/9.6/ppc64le/appstream/source/SRPMS',
      'content/e4s/rhel9/9.6/s390x/appstream/debug',
      'content/e4s/rhel9/9.6/s390x/appstream/os',
      'content/e4s/rhel9/9.6/s390x/appstream/source/SRPMS',
      'content/e4s/rhel9/9.6/x86_64/appstream/debug',
      'content/e4s/rhel9/9.6/x86_64/appstream/os',
      'content/e4s/rhel9/9.6/x86_64/appstream/source/SRPMS',
      'content/e4s/rhel9/rhui/9.6/x86_64/appstream/os',
      'content/e6s/rhel9/9.6/aarch64/appstream/debug',
      'content/e6s/rhel9/9.6/aarch64/appstream/os',
      'content/e6s/rhel9/9.6/aarch64/appstream/source/SRPMS',
      'content/e6s/rhel9/9.6/ppc64le/appstream/debug',
      'content/e6s/rhel9/9.6/ppc64le/appstream/os',
      'content/e6s/rhel9/9.6/ppc64le/appstream/source/SRPMS',
      'content/e6s/rhel9/9.6/s390x/appstream/debug',
      'content/e6s/rhel9/9.6/s390x/appstream/os',
      'content/e6s/rhel9/9.6/s390x/appstream/source/SRPMS',
      'content/e6s/rhel9/9.6/x86_64/appstream/debug',
      'content/e6s/rhel9/9.6/x86_64/appstream/os',
      'content/e6s/rhel9/9.6/x86_64/appstream/source/SRPMS',
      'content/eus/rhel9/9.6/aarch64/appstream/debug',
      'content/eus/rhel9/9.6/aarch64/appstream/os',
      'content/eus/rhel9/9.6/aarch64/appstream/source/SRPMS',
      'content/eus/rhel9/9.6/ppc64le/appstream/debug',
      'content/eus/rhel9/9.6/ppc64le/appstream/os',
      'content/eus/rhel9/9.6/ppc64le/appstream/source/SRPMS',
      'content/eus/rhel9/9.6/s390x/appstream/debug',
      'content/eus/rhel9/9.6/s390x/appstream/os',
      'content/eus/rhel9/9.6/s390x/appstream/source/SRPMS',
      'content/eus/rhel9/9.6/x86_64/appstream/debug',
      'content/eus/rhel9/9.6/x86_64/appstream/os',
      'content/eus/rhel9/9.6/x86_64/appstream/source/SRPMS',
      'content/eus/rhel9/rhui/9.6/x86_64/appstream/os'
    ],
    'pkgs': [
      {'reference':'nginx-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-all-modules-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-core-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-filesystem-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-http-image-filter-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-http-perl-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-http-xslt-filter-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-mail-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-stream-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'}
    ]
  },
  {
    'release': '9',
    'sp': '6',
    'repo_relative_urls': [
      'content/eus/rhel9/9.6/aarch64/codeready-builder/debug',
      'content/eus/rhel9/9.6/aarch64/codeready-builder/os',
      'content/eus/rhel9/9.6/aarch64/codeready-builder/source/SRPMS',
      'content/eus/rhel9/9.6/ppc64le/codeready-builder/debug',
      'content/eus/rhel9/9.6/ppc64le/codeready-builder/os',
      'content/eus/rhel9/9.6/ppc64le/codeready-builder/source/SRPMS',
      'content/eus/rhel9/9.6/s390x/codeready-builder/debug',
      'content/eus/rhel9/9.6/s390x/codeready-builder/os',
      'content/eus/rhel9/9.6/s390x/codeready-builder/source/SRPMS',
      'content/eus/rhel9/9.6/x86_64/codeready-builder/debug',
      'content/eus/rhel9/9.6/x86_64/codeready-builder/os',
      'content/eus/rhel9/9.6/x86_64/codeready-builder/source/SRPMS'
    ],
    'pkgs': [
      {'reference':'nginx-mod-devel-1.20.1-22.el9_6.7', 'sp':'6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'}
    ]
  }
];

var applicable_repo_urls = rhel_determine_applicable_repository_urls(constraints:constraints);
if(applicable_repo_urls == RHEL_REPOS_NO_OVERLAP_MESSAGE) exit(0, RHEL_REPO_NOT_ENABLED);

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var repo_relative_urls;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }

  if (!empty_or_null(constraint['repo_relative_urls'])) repo_relative_urls = constraint['repo_relative_urls'];

  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        rhel_decide_repo_relative_url_check(required_repo_url_list:repo_relative_urls) &&
        (applicable_repo_urls || (!exists_check || rpm_exists(rpm:exists_check))) &&
        rpm_check(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 subscription_caveat = '\n' +
    'NOTE: This vulnerability check contains fixes that apply to\n' +
    'packages only available in the Red Hat Enterprise Linux\n' +
    'Extended Update Support repository.\n' +
    'Access to this repository requires a paid RHEL subscription.\n';
  var extra = NULL;
  if (isnull(applicable_repo_urls) || !applicable_repo_urls) extra = subscription_caveat + rpm_report_get() + redhat_report_repo_caveat();
  else extra = subscription_caveat + rpm_report_get();
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : extra
  );
  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 / nginx-filesystem / etc');
}