TencentOS Server 4: nginx (TSSA-2026:0398)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2026:0398.
##

include('compat.inc');

if (description)
{
  script_id(319760);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/08");

  script_cve_id("CVE-2026-9256", "CVE-2026-40701");
  script_xref(name:"IAVA", value:"2026-A-0515");

  script_name(english:"TencentOS Server 4: nginx (TSSA-2026:0398)");

  script_set_attribute(attribute:"synopsis", value:
"The remote TencentOS Server 4 host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The version of Tencent Linux installed on the remote TencentOS Server 4 host is prior to tested version. It is,
therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0398 advisory.

    Package updates are available for TencentOS Server 4 that fix the following vulnerabilities:

    CVE-2026-9256:
    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-2026-40701:
    NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssl_modulemodule when the
    ssl_verify_clientdirective is set to on or optional, and the ssl_ocspdirective is set to on or
    the leafparameters 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.

Tenable has extracted the preceding description block directly from the Tencent 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://mirrors.tencent.com/tlinux/errata/tssa-20260398.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/C:P/I:N/A:P");
  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-2026-40701");
  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_set_attribute(attribute:"vuln_publication_date", value:"2026/05/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/04");
  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:"cpe:/o:tencent:tencentos_server:4");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:tencent:tencentos_server:nginx");
  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:"Tencent 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/etc/os-release", "Host/TencentOS/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.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) || 'TencentOS' >!< os_product) audit(AUDIT_OS_NOT, 'TencentOS');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'TencentOS');
if (! preg(pattern:"^4([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'TencentOS 4.x', 'TencentOS ' + os_version);

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

var constraints = [
  {
    'release': '4',
    'pkgs': [
      {'reference':'nginx-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-all-modules-1.26.3-1.tl4.ap.5', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-core-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-core-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-core-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-core-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-debugsource-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-debugsource-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-filesystem-1.26.3-1.tl4.ap.5', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-devel-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-devel-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-image-filter-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-image-filter-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-image-filter-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-image-filter-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-perl-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-perl-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-perl-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-perl-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-xslt-filter-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-xslt-filter-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-xslt-filter-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-xslt-filter-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-mail-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-mail-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-mail-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-mail-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-stream-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-stream-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-stream-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-stream-debuginfo-1.26.3-1.tl4.ap.5', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

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_WARNING,
      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');
}