Samba 4.21.x < 4.21.6 / 4.22.x < 4.22.2 Security Bypass Vulnerability

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

include('compat.inc');

if (description)
{
  script_id(237907);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/01/21");

  script_cve_id("CVE-2025-0620");
  script_xref(name:"IAVA", value:"2025-A-0397-S");

  script_name(english:"Samba 4.21.x < 4.21.6 / 4.22.x < 4.22.2 Security Bypass Vulnerability");

  script_set_attribute(attribute:"synopsis", value:
"The remote host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of Samba installed on the remote host is 4.21.x prior to 4.21.6, or 4.22.x prior to 4.22.2. It is, therefore,
affected by a security bypass vulnerability. A flaw exists with smbd when using Kerberos authentication with smb, due to
using the cached user group permissions when re-authenticating. An authenticated, remote attacker can exploit this, to
continue accessing a user group after being removed.

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://www.samba.org/samba/security/CVE-2025-0620.html");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.samba.org/show_bug.cgi?id=15707");
  script_set_attribute(attribute:"see_also", value:"https://www.samba.org/samba/history/samba-4.21.6.html");
  script_set_attribute(attribute:"see_also", value:"https://www.samba.org/samba/history/samba-4.22.2.html");
  script_set_attribute(attribute:"see_also", value:"https://www.openwall.com/lists/oss-security/2025/06/03/8");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Samba version 4.21.6, 4.22.2, or later.");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2025-0620");

  script_set_attribute(attribute:"vuln_publication_date", value:"2025/06/03");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/06/03");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/06/06");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:samba:samba");
  script_set_attribute(attribute:"stig_severity", value:"II");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2025-2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("smb_nativelanman.nasl");
  script_require_keys("SMB/samba", "SMB/NativeLanManager");

  exit(0);
}

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

var app_info = vcf::samba::get_app_info();

vcf::check_granularity(app_info:app_info, sig_segments:3);

var constraints = [
  { 'min_version' : '4.21', 'fixed_version' : '4.21.6' },
  { 'min_version' : '4.22', 'fixed_version' : '4.22.2' }
];

vcf::check_version_and_report(
    app_info:app_info,
    constraints:constraints,
    require_paranoia: TRUE,
    severity:SECURITY_WARNING
);