Linux Distros Unpatched Vulnerability : CVE-2026-22796

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

include('compat.inc');

if (description)
{
  script_id(296900);
  script_version("1.9");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/22");

  script_cve_id("CVE-2026-22796");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-22796");

  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.

  - Issue summary: A type confusion vulnerability exists in the signature verification of signed PKCS#7 data
    where an ASN1_TYPE union member is accessed without first validating the type, causing an invalid or NULL
    pointer dereference when processing malformed PKCS#7 data. Impact summary: An application performing
    signature verification of PKCS#7 data or calling directly the PKCS7_digest_from_attributes() function can
    be caused to dereference an invalid or NULL pointer when reading, resulting in a Denial of Service. The
    function PKCS7_digest_from_attributes() accesses the message digest attribute value without validating its
    type. When the type is not V_ASN1_OCTET_STRING, this results in accessing invalid memory through the
    ASN1_TYPE union, causing a crash. Exploiting this vulnerability requires an attacker to provide a
    malformed signed PKCS#7 to an application that verifies it. The impact of the exploit is just a Denial of
    Service, the PKCS7 API is legacy and applications should be using the CMS API instead. For these reasons
    the issue was assessed as Low severity. The FIPS modules in 3.5, 3.4, 3.3 and 3.0 are not affected by this
    issue, as the PKCS#7 parsing implementation is outside the OpenSSL FIPS module boundary. OpenSSL 3.6, 3.5,
    3.4, 3.3, 3.0, 1.1.1 and 1.0.2 are vulnerable to this issue. (CVE-2026-22796)

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-2026-22796");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-22796");
  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:M/Au:N/C:N/I:N/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:L");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-22796");

  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:"plugin_publication_date", value:"2026/01/27");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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: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:25.10");
  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:redhat:enterprise_linux:10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:6");
  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:edk2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:nodejs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:AAVMF");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:OVMF");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:compat-openssl10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:compat-openssl11");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2-aarch64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2-ovmf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2-tools-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:mingw32-openssl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:mingw64-openssl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:mokutil");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:openssl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:openssl-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:openssl-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:openssl-perl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:openssl-static");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:ovmf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:shim");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:shim-aa64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:shim-ia32");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:shim-unsigned-aarch64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:shim-unsigned-x64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:shim-x64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:AAVMF");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:OVMF");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:compat-openssl10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:compat-openssl11");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2-aarch64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2-ovmf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:edk2-tools-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:mingw32-openssl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:mingw64-openssl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:mokutil");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:openssl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:openssl-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:openssl-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:openssl-perl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:openssl-static");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:ovmf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-aa64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-ia32");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-unsigned-aarch64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-unsigned-x64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-x64");
  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/Red Hat Enterprise Linux-10", "Host/OS/Red Hat Enterprise Linux-6", "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-16.04", "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-25.10");

  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 = {
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "edk2"},
          {"reference": "nodejs"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "edk2"},
          {"reference": "nodejs"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "ovmf"},
          {"reference": "qemu-efi"},
          {"reference": "qemu-efi-aarch64"},
          {"reference": "qemu-efi-arm"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "nodejs"},
          {"reference": "ovmf"},
          {"reference": "ovmf-ia32"},
          {"reference": "qemu-efi"},
          {"reference": "qemu-efi-aarch64"},
          {"reference": "qemu-efi-arm"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "efi-shell-aa64"},
          {"reference": "efi-shell-arm"},
          {"reference": "efi-shell-ia32"},
          {"reference": "efi-shell-riscv64"},
          {"reference": "efi-shell-x64"},
          {"reference": "ovmf"},
          {"reference": "ovmf-ia32"},
          {"reference": "qemu-efi-aarch64"},
          {"reference": "qemu-efi-arm"},
          {"reference": "qemu-efi-riscv64"}
        ]
      }
    ]
  },
  "Ubuntu Linux-25.10": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "25.10",
        "pkgs": [
          {"reference": "efi-shell-aa64"},
          {"reference": "efi-shell-arm"},
          {"reference": "efi-shell-ia32"},
          {"reference": "efi-shell-loongarch64"},
          {"reference": "efi-shell-riscv64"},
          {"reference": "efi-shell-x64"},
          {"reference": "ovmf"},
          {"reference": "ovmf-ia32"},
          {"reference": "ovmf-inteltdx"},
          {"reference": "qemu-efi-aarch64"},
          {"reference": "qemu-efi-arm"},
          {"reference": "qemu-efi-loongarch64"},
          {"reference": "qemu-efi-riscv64"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "edk2-aarch64"},
          {"reference": "edk2-ovmf"},
          {"reference": "edk2-tools"},
          {"reference": "edk2-tools-doc"},
          {"reference": "mokutil"},
          {"reference": "shim-aa64"},
          {"reference": "shim-unsigned-aarch64"},
          {"reference": "shim-unsigned-x64"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-6": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "6",
        "pkgs": [
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-perl"},
          {"reference": "openssl-static"}
        ]
      }
    ]
  },
  "CentOS Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "AAVMF"},
          {"reference": "OVMF"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "openssl-static"},
          {"reference": "ovmf"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "AAVMF"},
          {"reference": "OVMF"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "openssl-static"},
          {"reference": "ovmf"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "compat-openssl10"},
          {"reference": "edk2"},
          {"reference": "edk2-aarch64"},
          {"reference": "edk2-ovmf"},
          {"reference": "mingw32-openssl"},
          {"reference": "mingw64-openssl"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "openssl-static"},
          {"reference": "shim"},
          {"reference": "shim-aa64"},
          {"reference": "shim-ia32"},
          {"reference": "shim-unsigned-x64"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "compat-openssl10"},
          {"reference": "edk2"},
          {"reference": "edk2-aarch64"},
          {"reference": "edk2-ovmf"},
          {"reference": "mingw32-openssl"},
          {"reference": "mingw64-openssl"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "openssl-static"},
          {"reference": "shim"},
          {"reference": "shim-aa64"},
          {"reference": "shim-ia32"},
          {"reference": "shim-unsigned-x64"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "compat-openssl11"},
          {"reference": "edk2"},
          {"reference": "edk2-aarch64"},
          {"reference": "edk2-ovmf"},
          {"reference": "edk2-tools"},
          {"reference": "edk2-tools-doc"},
          {"reference": "shim"},
          {"reference": "shim-aa64"},
          {"reference": "shim-unsigned-aarch64"},
          {"reference": "shim-unsigned-x64"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  }
};

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 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');
}