AlmaLinux 9.6 [TuxCare] Security Update: nginx / nginx-all-modules / nginx-core / nginx-filesystem / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1785509707)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(359805);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/01");

  script_cve_id(
    "CVE-2025-53859",
    "CVE-2026-28753",
    "CVE-2026-40701",
    "CVE-2026-42934",
    "CVE-2026-42946",
    "CVE-2026-48142"
  );
  script_xref(name:"CLSA", value:"2026:1785509707");

  script_name(english:"AlmaLinux 9.6 [TuxCare] Security Update: nginx / nginx-all-modules / nginx-core / nginx-filesystem / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1785509707)");

  script_set_attribute(attribute:"synopsis", value:
"The AlmaLinux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The AlmaLinux 9.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare
ALMALINUX9.6:CLSA-2026:1785509707 advisory.

  - NGINX Open Source and NGINX Plus have a vulnerability in the ngx_mail_smtp_module that might allow an
    unauthenticated attacker to over-read NGINX SMTP authentication process memory; as a result, the server
    side may leak arbitrary bytes sent in a request to the authentication server. This issue happens during
    the NGINX SMTP authentication process and requires the attacker to make preparations against the target
    system to extract the leaked data. The issue affects NGINX only if (1) it is built with the
    ngx_mail_smtp_module, (2) the smtp_auth directive is configured with method none, and (3) the
    authentication server returns the Auth-Wait response header. Note: Software versions which have reached
    End of Technical Support (EoTS) are not evaluated. (CVE-2025-53859)

  - NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the
    improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to
    inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note:
    Software versions which have reached End of Technical Support (EoTS) are not evaluated. (CVE-2026-28753)

  - NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssl_module module when the
    ssl_verify_client directive is set to on or optional, and the ssl_ocsp directive is set to on or the
    leaf parameters are configured with a resolver. With this configuration, an unauthenticated attacker can
    send requests along with conditions beyond its control that may cause a heap-use-after-free error in the
    NGINX worker process. This vulnerability may result in limited modification of data or the NGINX worker
    process restarting. Note: Software versions which have reached End of Technical Support (EoTS) are not
    evaluated. (CVE-2026-40701)

  - NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When charset,
    source_charset, and charset_map and proxy_pass with disabled buffering (off) directives are configured,
    unauthenticated attackers can send requests that with conditions beyond the attackers' control to cause a
    heap buffer over-read in the NGINX worker process, leading to limited disclosure of memory or a restart.
    Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
    (CVE-2026-42934)

  - A vulnerability exists in the ngx_http_scgi_module and ngx_http_uwsgi_module modules that may result in
    excessive memory allocation or an over-read of data. When scgi_pass or uwsgi_pass is configured, an
    unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream
    server may be able to read the memory of the NGINX worker process or restart it. Note: Software versions
    which have reached End of Technical Support (EoTS) are not evaluated. (CVE-2026-42946)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://security.tuxcare.com/csaf/v2/els_os/tuxcare9.6esu/advisories/2026/clsa-2026_1785509707.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?3eeda58a");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2026:1785509707");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages based on the guidance in TuxCare advisory ALMALINUX9.6:CLSA-2026:1785509707.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/C:C/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:H/PR:N/UI:N/S:U/C:H/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-42946");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_severity", value:"Important");

  script_set_attribute(attribute:"vuln_publication_date", value:"2025/08/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/31");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/01");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Alma 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/OS/extended-third-party", "Host/local_checks_enabled", "Host/AlmaLinux/release", "Host/AlmaLinux/rpm-list", "Host/cpu");

  exit(0);
}
include('rpm2.inc');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (empty_or_null(third_party_support) || third_party_support != 'TuxCare') exit(0, 'TuxCare support not enabled.');

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) || 'AlmaLinux' >!< os_product) audit(AUDIT_OS_NOT, 'AlmaLinux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'AlmaLinux');
if (! preg(pattern:"^9.6([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'AlmaLinux 9.6', 'AlmaLinux ' + os_version);

if (!get_kb_item('Host/AlmaLinux/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) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'AlmaLinux', cpu);


var constraints = [
  {
    'release': '9',
    'sp': '6',
    'pkgs': [
      {'reference':'nginx-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-all-modules-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-core-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-filesystem-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-devel-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-http-image-filter-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-http-perl-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-http-xslt-filter-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-mail-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'},
      {'reference':'nginx-mod-stream-1.20.1-22.el9_6.3.alma.2.tuxcare.els9', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_6', 'rpm_spec_vers_cmp':TRUE, 'epoch':'2'}
    ]
  }
];

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 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;
  }
  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 &&
        ## (no known rpm to check OR known rpm_exists)
        (!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)
{
  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 / nginx-filesystem / etc');
}