TencentOS Server 4: nginx (TSSA-2026:0549)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2026:0549.
##

include('compat.inc');

if (description)
{
  script_id(325860);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/09");

  script_cve_id("CVE-2026-42055");
  script_xref(name:"IAVA", value:"2026-A-0601");

  script_name(english:"TencentOS Server 4: nginx (TSSA-2026:0549)");

  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 a vulnerability as referenced in the TSSA-2026:0549 advisory.

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

    CVE-2026-42055:
    NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_proxy_v2_module and
    ngx_http_grpc_module modules. This vulnerability exists when the proxy_http_version to 2 or grpc_pass
    directives are used to proxy HTTP/2 traffic, the ignore_invalid_headers directive is set to off, and the
    large_client_header_buffers directive size is larger than 2 megabytes. A remote, unauthenticated attacker,
    along with conditions beyond their control, could send large headers while creating an upstream request.
    This may cause a heap-based 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.

Tenable has extracted the preceding description block directly from the Tencent Linux 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://mirrors.tencent.com/tlinux/errata/tssa-20260549.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  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: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:H/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: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:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-42055");

  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:"2026/06/17");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/06");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/09");

  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.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-all-modules-1.26.3-1.tl4.ap.6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-core-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-core-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-core-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-core-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-debugsource-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-debugsource-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-filesystem-1.26.3-1.tl4.ap.6', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-devel-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-devel-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-image-filter-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-image-filter-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-image-filter-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-image-filter-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-perl-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-perl-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-perl-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-perl-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-xslt-filter-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-xslt-filter-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-xslt-filter-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-http-xslt-filter-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-mail-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-mail-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-mail-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-mail-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-stream-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-stream-1.26.3-1.tl4.ap.6', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-stream-debuginfo-1.26.3-1.tl4.ap.6', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'nginx-mod-stream-debuginfo-1.26.3-1.tl4.ap.6', '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_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');
}