Linux Distros Unpatched Vulnerability : CVE-2026-58221

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

include('compat.inc');

if (description)
{
  script_id(330478);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/29");

  script_cve_id("CVE-2026-58221");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-58221");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - Samba AD stores internal database configuration in LDB special records such as @MODULES and @PARTITION.
    These records are not directory objects and should never be writable by a normal LDAP client. An
    authenticated low-privilege domain user can nevertheless modify them through LDAP. The LDAP request is
    correctly marked as untrusted, but `rootdse_filter_operations()` only rejects anonymous callers. The
    request then reaches the DSDB ACL module, which intentionally skips ACL processing for special DNs because
    it assumes only trusted internal callers can reach them. This lets an ordinary user replace the DSDB
    module chain loaded for new LDAP connections. By omitting only acl and aclread, the attacker gets a fully
    functional LDAP connection without directory ACL enforcement and can add themselves to protected
    administrator groups. High-signal indicators: - A recent modification timestamp of the main sam.ldb most
    likely: /var/lib/samba/private/sam.ldb - LDAP operations targeting DNs beginning with `@`; -
    `@MODULES/@LIST` differing from `samba_dsdb`; - unexpected `@PARTITION/modules` values on a standard
    provision; - low-privilege accounts added to `Domain Admins`, `Enterprise Admins`, or `Builtin
    Administrators`; - Samba logs showing unusual module-load failures or module-stack changes. If
    exploitation is suspected: 1. Stop Samba before editing internal LDB records offline. 2. Confirm
    `@MODULES/@LIST` is exactly `samba_dsdb`. 3. Remove unexpected `@PARTITION/modules` values offline if
    present. 4. Remove unauthorized protected-group memberships. 5. Audit privileged group, ACL, GPO/SYSVOL,
    service-account, and replication changes made during the compromise window. 6. Rotate credentials
    according to the site's AD recovery plan, including KRBTGT where appropriate. (CVE-2026-58221)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-58221");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-58221");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-58221");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_unpatched", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/07/28");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/29");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:11.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:12.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:14.0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:samba");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:samba");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

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

  script_dependencies("ssh_get_info2.nasl", "set_linux_os_id.nasl");
  script_require_keys("Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched", "Host/OS/identifier");
  script_require_ports("Host/OS/Debian Linux-11", "Host/OS/Debian Linux-12", "Host/OS/Debian Linux-14", "Host/OS/Ubuntu Linux-14.04", "Host/OS/Ubuntu Linux-16.04", "Host/OS/Ubuntu Linux-18.04", "Host/OS/Ubuntu Linux-20.04");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/Debian/dpkg-l"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Debian Linux-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "ctdb"},
          {"reference": "ldb-tools"},
          {"reference": "libldb-dev"},
          {"reference": "libldb2"},
          {"reference": "libnss-winbind"},
          {"reference": "libpam-winbind"},
          {"reference": "libsmbclient"},
          {"reference": "libsmbclient-dev"},
          {"reference": "libwbclient-dev"},
          {"reference": "libwbclient0"},
          {"reference": "python3-ldb"},
          {"reference": "python3-ldb-dev"},
          {"reference": "python3-samba"},
          {"reference": "registry-tools"},
          {"reference": "samba"},
          {"reference": "samba-ad-dc"},
          {"reference": "samba-ad-provision"},
          {"reference": "samba-common"},
          {"reference": "samba-common-bin"},
          {"reference": "samba-dev"},
          {"reference": "samba-dsdb-modules"},
          {"reference": "samba-libs"},
          {"reference": "samba-testsuite"},
          {"reference": "samba-vfs-modules"},
          {"reference": "smbclient"},
          {"reference": "winbind"}
        ]
      }
    ]
  },
  "Debian Linux-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "ctdb"},
          {"reference": "libnss-winbind"},
          {"reference": "libpam-winbind"},
          {"reference": "libsmbclient"},
          {"reference": "libsmbclient-dev"},
          {"reference": "libwbclient-dev"},
          {"reference": "libwbclient0"},
          {"reference": "python3-samba"},
          {"reference": "registry-tools"},
          {"reference": "samba"},
          {"reference": "samba-common"},
          {"reference": "samba-common-bin"},
          {"reference": "samba-dev"},
          {"reference": "samba-dsdb-modules"},
          {"reference": "samba-libs"},
          {"reference": "samba-testsuite"},
          {"reference": "samba-vfs-modules"},
          {"reference": "smbclient"},
          {"reference": "winbind"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "ctdb"},
          {"reference": "libnss-winbind"},
          {"reference": "libpam-winbind"},
          {"reference": "libsmbclient"},
          {"reference": "libsmbclient-dev"},
          {"reference": "libwbclient-dev"},
          {"reference": "libwbclient0"},
          {"reference": "python3-samba"},
          {"reference": "registry-tools"},
          {"reference": "samba"},
          {"reference": "samba-common"},
          {"reference": "samba-common-bin"},
          {"reference": "samba-dev"},
          {"reference": "samba-dsdb-modules"},
          {"reference": "samba-libs"},
          {"reference": "samba-testsuite"},
          {"reference": "samba-vfs-modules"},
          {"reference": "smbclient"},
          {"reference": "winbind"}
        ]
      }
    ]
  },
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "ctdb"},
          {"reference": "ldb-tools"},
          {"reference": "libldb-dev"},
          {"reference": "libldb2"},
          {"reference": "libnss-winbind"},
          {"reference": "libpam-winbind"},
          {"reference": "libsmbclient"},
          {"reference": "libsmbclient-dev"},
          {"reference": "libsmbclient0"},
          {"reference": "libtalloc-dev"},
          {"reference": "libtalloc2"},
          {"reference": "libtdb-dev"},
          {"reference": "libtdb1"},
          {"reference": "libtevent-dev"},
          {"reference": "libtevent0"},
          {"reference": "libtevent0t64"},
          {"reference": "libwbclient-dev"},
          {"reference": "libwbclient0"},
          {"reference": "python3-ldb"},
          {"reference": "python3-samba"},
          {"reference": "python3-talloc"},
          {"reference": "python3-tdb"},
          {"reference": "registry-tools"},
          {"reference": "samba"},
          {"reference": "samba-ad-dc"},
          {"reference": "samba-ad-provision"},
          {"reference": "samba-common"},
          {"reference": "samba-common-bin"},
          {"reference": "samba-dev"},
          {"reference": "samba-dsdb-modules"},
          {"reference": "samba-libs"},
          {"reference": "samba-testsuite"},
          {"reference": "samba-vfs-ceph"},
          {"reference": "samba-vfs-glusterfs"},
          {"reference": "samba-vfs-modules"},
          {"reference": "smbclient"},
          {"reference": "tdb-tools"},
          {"reference": "winbind"}
        ]
      }
    ]
  },
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "libnss-winbind"},
          {"reference": "libpam-smbpass"},
          {"reference": "libpam-winbind"},
          {"reference": "libparse-pidl-perl"},
          {"reference": "libsmbclient"},
          {"reference": "libsmbclient-dev"},
          {"reference": "libsmbsharemodes-dev"},
          {"reference": "libsmbsharemodes0"},
          {"reference": "libwbclient-dev"},
          {"reference": "libwbclient0"},
          {"reference": "python-samba"},
          {"reference": "registry-tools"},
          {"reference": "samba"},
          {"reference": "samba-common"},
          {"reference": "samba-common-bin"},
          {"reference": "samba-dbg"},
          {"reference": "samba-dev"},
          {"reference": "samba-doc"},
          {"reference": "samba-dsdb-modules"},
          {"reference": "samba-libs"},
          {"reference": "samba-testsuite"},
          {"reference": "samba-vfs-modules"},
          {"reference": "smbclient"},
          {"reference": "winbind"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "ctdb"},
          {"reference": "libnss-winbind"},
          {"reference": "libpam-winbind"},
          {"reference": "libparse-pidl-perl"},
          {"reference": "libsmbclient"},
          {"reference": "libsmbclient-dev"},
          {"reference": "libwbclient-dev"},
          {"reference": "libwbclient0"},
          {"reference": "python-samba"},
          {"reference": "registry-tools"},
          {"reference": "samba"},
          {"reference": "samba-common"},
          {"reference": "samba-common-bin"},
          {"reference": "samba-dbg"},
          {"reference": "samba-dev"},
          {"reference": "samba-dsdb-modules"},
          {"reference": "samba-libs"},
          {"reference": "samba-testsuite"},
          {"reference": "samba-vfs-modules"},
          {"reference": "smbclient"},
          {"reference": "winbind"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "ctdb"},
          {"reference": "libnss-winbind"},
          {"reference": "libpam-winbind"},
          {"reference": "libparse-pidl-perl"},
          {"reference": "libsmbclient"},
          {"reference": "libsmbclient-dev"},
          {"reference": "libwbclient-dev"},
          {"reference": "libwbclient0"},
          {"reference": "python-samba"},
          {"reference": "registry-tools"},
          {"reference": "samba"},
          {"reference": "samba-common"},
          {"reference": "samba-common-bin"},
          {"reference": "samba-dev"},
          {"reference": "samba-dsdb-modules"},
          {"reference": "samba-libs"},
          {"reference": "samba-testsuite"},
          {"reference": "samba-vfs-modules"},
          {"reference": "smbclient"},
          {"reference": "winbind"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (!empty_or_null(third_party_support)) {
    var third_party_vendors = distro_constraints_values['third_party'];
    if (!empty_or_null(third_party_vendors)) {
        var vendor;
        foreach vendor (third_party_vendors) {
            if (vendor == third_party_support) exit(0, 'A third party management patch is available for this vulnerability from ' + vendor + '.\n');
        }
    }
}

var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}