nginx 1.27.2 < 1.28.3 / 1.29.x < 1.29.7 OCSP Result Bypass

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

include('compat.inc');

if (description)
{
  script_id(306672);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/04/17");

  script_cve_id("CVE-2026-28755");

  script_name(english:"nginx 1.27.2 < 1.28.3 / 1.29.x < 1.29.7 OCSP Result Bypass");

  script_set_attribute(attribute:"synopsis", value:
"The remote web server is affected by a vulnerability.");
  script_set_attribute(attribute:"description", value:
"The installed version of nginx is 1.27.2 prior to 1.28.3, or 1.29.x prior to 1.29.7. It is, therefore, affected by
the following issue :

  - NGINX Plus and NGINX Open Source have a vulnerability in the ngx_stream_ssl_module module due to the
    improper handling of revoked certificates when configured with the ssl_verify_client on and ssl_ocsp on
    directives, allowing the TLS handshake to succeed even after an OCSP check identifies the certificate
    as revoked. Note: Software versions which have reached End of Technical Support (EoTS) are not
    evaluated. (CVE-2026-28755)

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/K000160368");
  script_set_attribute(attribute:"see_also", value:"https://nginx.org/en/security_advisories.html");
  script_set_attribute(attribute:"solution", value:
"Upgrade to nginx 1.28.3 / 1.29.7 or later.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:P/I:P/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N");
  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:N/PR:L/UI:N/VC:L/VI:L/VA:N/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-2026-28755");

  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:"2026/03/24");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/03/24");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/04/16");

  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_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');

# ngx_stream_ssl_module is not compiled by default
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' : '1.27.2', 'fixed_version' : '1.28.3' },
  { 'min_version' : '1.29.0', 'fixed_version' : '1.29.7' }
];
vcf::check_version_and_report(
    app_info:app_info,
    constraints:constraints,
    severity:SECURITY_WARNING
);