Linux Distros Unpatched Vulnerability : CVE-2026-42391

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

include('compat.inc');

if (description)
{
  script_id(341518);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/29");

  script_cve_id("CVE-2026-42391");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-42391");

  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.

  - An unauthenticated attacker can send an IMAP ID command with a very large number of parameters before
    logging in, which causes memory and CPU usage to grow disproportionately. The login process can be
    terminated by the out-of-memory handling, which also terminates all other connections handled by the same
    process. This can cause degradation or denial of service for IMAP logins. Limit the number of connections
    handled by a single imap-login process. This has a performance impact though. Update to non-vulnerable
    version. No publicly available exploits are known. (CVE-2026-42391)

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-2026-42391");
  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:N/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:N/UI:N/S:U/C:N/I:N/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-2026-42391");

  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:"2026/08/28");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/29");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:13.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:14.0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:dovecot");
  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-13", "Host/OS/Debian Linux-14");

  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-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "dovecot-auth-lua"},
          {"reference": "dovecot-core"},
          {"reference": "dovecot-dev"},
          {"reference": "dovecot-gssapi"},
          {"reference": "dovecot-imapd"},
          {"reference": "dovecot-ldap"},
          {"reference": "dovecot-lmtpd"},
          {"reference": "dovecot-lucene"},
          {"reference": "dovecot-managesieved"},
          {"reference": "dovecot-mysql"},
          {"reference": "dovecot-pgsql"},
          {"reference": "dovecot-pop3d"},
          {"reference": "dovecot-sieve"},
          {"reference": "dovecot-solr"},
          {"reference": "dovecot-sqlite"},
          {"reference": "dovecot-submissiond"}
        ]
      }
    ]
  },
  "Debian Linux-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "dovecot-auth-lua"},
          {"reference": "dovecot-core"},
          {"reference": "dovecot-dev"},
          {"reference": "dovecot-gssapi"},
          {"reference": "dovecot-imapd"},
          {"reference": "dovecot-ldap"},
          {"reference": "dovecot-lmtpd"},
          {"reference": "dovecot-lucene"},
          {"reference": "dovecot-managesieved"},
          {"reference": "dovecot-mysql"},
          {"reference": "dovecot-pgsql"},
          {"reference": "dovecot-pop3d"},
          {"reference": "dovecot-sieve"},
          {"reference": "dovecot-solr"},
          {"reference": "dovecot-sqlite"},
          {"reference": "dovecot-submissiond"}
        ]
      }
    ]
  },
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "dovecot-auth-lua"},
          {"reference": "dovecot-core"},
          {"reference": "dovecot-dev"},
          {"reference": "dovecot-flatcurve"},
          {"reference": "dovecot-gssapi"},
          {"reference": "dovecot-imapd"},
          {"reference": "dovecot-ldap"},
          {"reference": "dovecot-lmtpd"},
          {"reference": "dovecot-managesieved"},
          {"reference": "dovecot-mariadb"},
          {"reference": "dovecot-mysql"},
          {"reference": "dovecot-pgsql"},
          {"reference": "dovecot-pop3d"},
          {"reference": "dovecot-sieve"},
          {"reference": "dovecot-solr"},
          {"reference": "dovecot-sqlite"},
          {"reference": "dovecot-submissiond"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "dovecot-auth-lua"},
          {"reference": "dovecot-core"},
          {"reference": "dovecot-dev"},
          {"reference": "dovecot-flatcurve"},
          {"reference": "dovecot-gssapi"},
          {"reference": "dovecot-imapd"},
          {"reference": "dovecot-ldap"},
          {"reference": "dovecot-lmtpd"},
          {"reference": "dovecot-managesieved"},
          {"reference": "dovecot-mysql"},
          {"reference": "dovecot-pgsql"},
          {"reference": "dovecot-pop3d"},
          {"reference": "dovecot-sieve"},
          {"reference": "dovecot-solr"},
          {"reference": "dovecot-sqlite"},
          {"reference": "dovecot-submissiond"}
        ]
      }
    ]
  }
};

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');
}