nginx 0.5.13 < 1.28.3 / 1.29.x < 1.29.7 Buffer Overflow in ngx_http_dav_module

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

include('compat.inc');

if (description)
{
  script_id(306674);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/04/17");

  script_cve_id("CVE-2026-27654");

  script_name(english:"nginx 0.5.13 < 1.28.3 / 1.29.x < 1.29.7 Buffer Overflow in ngx_http_dav_module");

  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 0.5.13 prior to 1.28.3, or 1.29.x prior to 1.29.7. It is, therefore, affected by
the following issue :

  - NGINX Open Source and NGINX Plus have a vulnerability in the ngx_http_dav_module module that might
    allow an attacker to trigger a buffer overflow to the NGINX worker process; this vulnerability may
    result in termination of the NGINX worker process or modification of source or destination file names
    outside the document root. This issue affects NGINX Open Source and NGINX Plus when the configuration
    file uses DAV module MOVE or COPY methods, prefix location (nonregular expression location
    configuration), and alias directives. The integrity impact is constrained because the NGINX worker
    process user has low privileges and does not have access to the entire system. Note: Software versions
    which have reached End of Technical Support (EoTS) are not evaluated. (CVE-2026-27654)

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/K000160382");
  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:N/C:N/I:P/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-27654");

  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:"2026/03/24");
  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_http_dav_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' : '0.5.13', '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_HOLE
);