Linux Distros Unpatched Vulnerability : CVE-2026-96808

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

include('compat.inc');

if (description)
{
  script_id(349599);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/25");

  script_cve_id("CVE-2026-96808");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-96808");

  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.

  - In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository
    data from unprivileged callers, validated file paths by rejecting literal .. components but did not
    prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs
    sessions via the system helper, create a symlink in one session pointing into the other session's
    directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files
    belonging to a different revokefs session after they had been validated and imported by the system helper.
    In particular, an attacker could use this to tamper with ostree commit objects in the system repository
    after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths
    and local root privilege escalation. (CVE-2026-96808)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/cve-2026-96808");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-96808");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-96808");
  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:L/AC:H/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:H/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:"cvss_score_source", value:"CVE-2026-96808");

  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:"2026/09/23");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/24");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:24.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:centos:centos:7");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:centos:centos:8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:12.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:7");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:9");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:flatpak");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:flatpak");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:flatpak-builder");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:flatpak-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:flatpak-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:flatpak-selinux");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:flatpak-session-helper");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:flatpak");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:flatpak");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:flatpak-builder");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:flatpak-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:flatpak-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:flatpak-selinux");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:flatpak-session-helper");
  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/CentOS Linux-7", "Host/OS/CentOS Linux-8", "Host/OS/Debian Linux-12", "Host/OS/Red Hat Enterprise Linux-10", "Host/OS/Red Hat Enterprise Linux-7", "Host/OS/Red Hat Enterprise Linux-8", "Host/OS/Red Hat Enterprise Linux-9", "Host/OS/Ubuntu Linux-18.04", "Host/OS/Ubuntu Linux-20.04", "Host/OS/Ubuntu Linux-22.04", "Host/OS/Ubuntu Linux-24.04", "Host/OS/Ubuntu Linux-26.04");

  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/CentOS/rpm-list")) && empty_or_null(get_one_kb_item("Host/Debian/dpkg-l")) && empty_or_null(get_one_kb_item("Host/RedHat/rpm-list"))) 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": "flatpak"},
          {"reference": "flatpak-tests"},
          {"reference": "gir1.2-flatpak-1.0"},
          {"reference": "libflatpak-dev"},
          {"reference": "libflatpak-doc"},
          {"reference": "libflatpak0"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "flatpak"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "flatpak"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "flatpak"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "flatpak"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "flatpak"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "flatpak"},
          {"reference": "flatpak-devel"},
          {"reference": "flatpak-libs"},
          {"reference": "flatpak-selinux"},
          {"reference": "flatpak-session-helper"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "flatpak"},
          {"reference": "flatpak-devel"},
          {"reference": "flatpak-libs"},
          {"reference": "flatpak-selinux"},
          {"reference": "flatpak-session-helper"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "flatpak"},
          {"reference": "flatpak-devel"},
          {"reference": "flatpak-libs"},
          {"reference": "flatpak-selinux"},
          {"reference": "flatpak-session-helper"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "flatpak"},
          {"reference": "flatpak-devel"},
          {"reference": "flatpak-libs"},
          {"reference": "flatpak-selinux"},
          {"reference": "flatpak-session-helper"}
        ]
      }
    ]
  },
  "CentOS Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "flatpak"},
          {"reference": "flatpak-builder"},
          {"reference": "flatpak-devel"},
          {"reference": "flatpak-libs"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "flatpak"},
          {"reference": "flatpak-builder"},
          {"reference": "flatpak-devel"},
          {"reference": "flatpak-libs"}
        ]
      }
    ]
  }
};

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');
}