OpenSSL 4.0.0 < 4.0.2 Vulnerability

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

include('compat.inc');

if (description)
{
  script_id(332232);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/05");

  script_cve_id("CVE-2026-54876");

  script_name(english:"OpenSSL 4.0.0 < 4.0.2 Vulnerability");

  script_set_attribute(attribute:"synopsis", value:
"The remote service is affected by a vulnerability.");
  script_set_attribute(attribute:"description", value:
"The version of OpenSSL installed on the remote host is prior to 4.0.2. It is, therefore, affected by a vulnerability as
referenced in the 4.0.2 advisory.

  - Issue summary: A malicious TLS server can cause a memory leak in a TLS client that has enabled OCSP
    response checking by sending an OCSP response that contains no single response entries. Impact summary: An
    attacker can leak an attacker-tunable amount of memory per TLS handshake in a victim client application. A
    long-running client that repeatedly connects to a malicious server can have its memory exhausted,
    resulting in a Denial of Service. CWE: CWE-401: Missing Release of Memory after Effective Lifetime
    Description: The affected function is called during X.509 certificate chain verification when OCSP
    response checking is enabled with the X509_V_FLAG_OCSP_RESP_CHECK or X509_V_FLAG_OCSP_RESP_CHECK_ALL
    verification flags, for example when a TLS client verifies an OCSP response stapled into the TLS handshake
    by the server. When the received BasicOCSPResponse contains an empty SEQUENCE OF SingleResponse, which is
    permitted on the wire and accepted by the OpenSSL decoder, the OCSP_BASICRESP structure allocated by
    OCSP_response_get1_basic() was not freed because an early return bypassed the cleanup code at the end of
    the function. The amount of memory leaked per handshake can be amplified by the attacker by padding the
    certs field of the BasicOCSPResponse with bogus certificates, which are parsed and stored in the leaked
    structure before the empty response check triggers the early return. A long-running TLS client that
    repeatedly connects to a malicious server can have its memory exhausted over time. OCSP response checking
    is not enabled by default. Only client applications that explicitly enable the OCSP response check
    verification flags are affected. FIPS impact: no The FIPS modules in 4.0 and 3.6 are not affected by this
    issue as the affected code is outside the OpenSSL FIPS module boundary. (CVE-2026-54876)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  # https://github.com/openssl/openssl/commit/d8c51048ac037a21bae0f41cad7a3920dc7f3638
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?715837e5");
  script_set_attribute(attribute:"see_also", value:"https://openssl-library.org/news/secadv/20260805.txt");
  # https://openssl-library.org/policies/general/security-policy/index.html
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?eac4598c");
  script_set_attribute(attribute:"see_also", value:"https://www.cve.org/CVERecord?id=CVE-2026-54876");
  script_set_attribute(attribute:"solution", value:
"Upgrade to OpenSSL version 4.0.2 or later.");
  script_set_attribute(attribute:"agent", value:"all");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:N/I:N/A:P");
  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:N/UI:N/S:U/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-54876");

  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:"2026/08/05");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/05");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/05");

  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:openssl:openssl");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"thorough_tests", value:"true");
  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("openssl_version.nasl", "openssl_nix_installed.nbin", "openssl_win_installed.nbin");
  script_require_keys("installed_sw/OpenSSL");

  exit(0);
}

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

var app_info = vcf::combined_get_app_info(app:'OpenSSL');

vcf::check_all_backporting(app_info:app_info);

var constraints = [
  { 'min_version' : '4.0.0', 'fixed_version' : '4.0.2' }
];

vcf::openssl::check_version_and_report(
    app_info:app_info,
    constraints:constraints,
    severity:SECURITY_WARNING
);