Linux Distros Unpatched Vulnerability : CVE-2026-95834

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

include('compat.inc');

if (description)
{
  script_id(350747);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/25");

  script_cve_id("CVE-2026-95834");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-95834");

  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.

  - Use After Free in the drag source path of the drag and drop protocol in kitty from 0.47.0 before 0.49.0
    allows a program writing to the terminal to cause the terminal to read from and write to freed heap
    memory, because drag_remote_file_data() in kitty/dnd.c holds a DragRemoteItem pointer into an array it
    does not own, calls toplevel_data_for_drag() or subdir_data_for_drag(), and then continues to use that
    pointer. Those helpers, and add_payload() and populate_dir_entries() which they call, report errors
    through the abrt() macro, which expands to cancel_drag() followed by a plain return, and cancel_drag()
    calls drag_free_offer(), which frees the array the pointer refers to. The helpers return void, so the
    caller receives no indication that the teardown happened, and proceeds to call all_children_complete() on
    the freed pointer, which dereferences it, and then to write through it. That dereference is guarded by a
    local flag that is set when the request carries no payload and announces no further data, which is the
    same condition that selects the finalisation block of add_payload(), so the error paths in that block
    reach it: a create that fails because an entry of the same name already exists, because the client may
    declare two entries with one name and the create operations use O_CREAT with O_EXCL and symlinkat(), a
    mkdirat() failure other than EEXIST, and the directory entry allocation paths. Both branches reach it. In
    the top level branch the caller's pointer is never cleared, so clearing the owning structure's own
    pointers during teardown does not help. In the sub directory branch subdir_data_for_drag() sets the
    caller's pointer to NULL on entry and assigns it only after its own last error path, so its own aborts
    leave the caller with NULL and are stopped by a null check, but it then calls add_payload() with that
    pointer set, and an abort there leaves the caller holding a freed child node inside the item tree, which
    drag_free_offer() frees by recursion. This results in undefined behaviour in the terminal process,
    reachable from the byte stream of any program running in the window. (CVE-2026-95834)

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-2026-95834");
  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:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-95834");

  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:"2026/09/25");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:kitty");
  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-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-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "kitty"},
          {"reference": "kitty-doc"},
          {"reference": "kitty-shell-integration"},
          {"reference": "kitty-terminfo"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "kitty"},
          {"reference": "kitty-doc"},
          {"reference": "kitty-shell-integration"},
          {"reference": "kitty-terminfo"}
        ]
      }
    ]
  },
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "kitty"},
          {"reference": "kitty-doc"},
          {"reference": "kitty-shell-integration"},
          {"reference": "kitty-terminfo"}
        ]
      }
    ]
  }
};

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');
}