nginx 1.30.x < 1.30.4 / 1.31.2 < 1.31.3 Multiple Vulnerabilities

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

include('compat.inc');

if (description)
{
  script_id(330084);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/27");

  script_cve_id("CVE-2026-42533", "CVE-2026-56434", "CVE-2026-60005");
  script_xref(name:"IAVA", value:"2026-A-0754");

  script_name(english:"nginx 1.30.x < 1.30.4 / 1.31.2 < 1.31.3 Multiple Vulnerabilities");

  script_set_attribute(attribute:"synopsis", value:
"The remote web server is affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"According to its Server response header, the installed version of nginx is 1.30.0 prior to 1.30.4, or 1.31.2 prior to
1.31.3. It is, therefore, affected by multiple vulnerabilities:

  - A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a
    string expression references the map's regex capture variables before referencing the map output variable.
    Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression
    under certain conditions. 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. Impact: This vulnerability may
    allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code
    execution. There is no control plane exposure; this is a data plane issue only. (CVE-2026-42533)

  - NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability
    may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured.
    With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control
    responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This
    issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This
    vulnerability may allow remote attackers to have limited control to modify memory contents or restart the
    NGINX worker process. There is no control plane exposure; this is a data plane issue only. (CVE-2026-56434)

  - NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_slice_module module. When the slice
    directive and unnamed regex captures are configured or when a background cache update happens,
    unauthenticated attackers can send requests that may cause uninitialized memory access in the NGINX worker
    process, leading to limited disclosure of memory or a restart. Impact: This vulnerability may allow remote,
    unauthenticated attackers to have limited control to disclose memory contents or restart the NGINX worker
    process. There is no control plane exposure; this is a data plane issue only. Note: The 
    ngx_http_slice_module module is not enabled by default; it's enabled with the --with-http_slice_module
    configuration parameter. (CVE-2026-60005)

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://my.f5.com/manage/s/article/K000162097");
  script_set_attribute(attribute:"see_also", value:"https://my.f5.com/manage/s/article/K000162098");
  script_set_attribute(attribute:"see_also", value:"https://my.f5.com/manage/s/article/K000162100");
  script_set_attribute(attribute:"see_also", value:"https://nginx.org/en/security_advisories.html");
  script_set_attribute(attribute:"solution", value:
"Upgrade to nginx 1.30.4, 1.31.3 or later.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-60005");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/07/15");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/15");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/27");

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:nginx:nginx");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Web Servers");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("nginx_detect.nasl", "nginx_nix_installed.nbin");
  script_require_keys("Settings/ParanoidReport", "installed_sw/nginx");

  exit(0);
}

include('vcf.inc');
include('http.inc');

# requires a 'map' directive using specific regex (CVE-2026-42533)
# ngx_http_ssi_module requires 'proxy_pass' and 'proxy_buffering off' directives to be configured (CVE-2026-56434)
# requires ngx_http_slice_module to be enabled, which it is not by default (CVE-2026-60005)
if (report_paranoia < 2)
  audit(AUDIT_PARANOID);

var appname = 'nginx';
get_install_count(app_name:appname, exit_if_zero:TRUE);

var app_info = vcf::combined_get_app_info(app:appname);
vcf::check_granularity(app_info:app_info, sig_segments:3);

var constraints = [
  { 'min_version' : '1.30.0', 'fixed_version' : '1.30.4', 'fixed_display' : '1.30.4 / 1.31.3'},
  { 'min_version' : '1.31.2', 'fixed_version' : '1.31.3' }
];
vcf::check_version_and_report(
    app_info:app_info,
    constraints:constraints,
    severity:SECURITY_HOLE
);