Linux Distros Unpatched Vulnerability : CVE-2026-33186

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

include('compat.inc');

if (description)
{
  script_id(303458);
  script_version("1.22");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/08");

  script_cve_id("CVE-2026-33186");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-33186");

  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.

  - gRPC-Go is the Go language implementation of gRPC. Versions prior to 1.79.3 have an authorization bypass
    resulting from improper input validation of the HTTP/2 `:path` pseudo-header. The gRPC-Go server was too
    lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash
    (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests
    to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated
    the raw, non-canonical path string. Consequently, deny rules defined using canonical paths (starting
    with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback allow
    rule was present. This affects gRPC-Go servers that use path-based authorization interceptors, such as the
    official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on
    `info.FullMethod` or `grpc.Method(ctx)`; AND that have a security policy contains specific deny rules
    for canonical paths but allows other requests by default (a fallback allow rule). The vulnerability is
    exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the
    gRPC server. The fix in version 1.79.3 ensures that any request with a `:path` that does not start with a
    leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching
    authorization interceptors or handlers with a non-canonical path string. While upgrading is the most
    secure and recommended path, users can mitigate the vulnerability using one of the following methods: Use
    a validating interceptor (recommended mitigation); infrastructure-level normalization; and/or policy
    hardening. (CVE-2026-33186)

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-2026-33186");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-33186");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-33186");
  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:N/I:C/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:POC/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:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-33186");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"vendor_unpatched", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/03/18");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/03/24");

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  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: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: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: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:golang-google-grpc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:google-guest-agent");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:ignition");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:ignition-edge");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:ignition-grub");
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  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:rhc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:rhc-worker-script");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:golang-google-grpc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:ignition");
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  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:ignition-validate");
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  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-11", "Host/OS/Debian Linux-12", "Host/OS/Debian Linux-13", "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-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", "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": "golang-google-grpc-dev"},
          {"reference": "protoc-gen-go-grpc"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "golang-google-grpc-dev"},
          {"reference": "protoc-gen-go-grpc"}
        ]
      }
    ]
  },
  "Debian Linux-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "golang-google-grpc-dev"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "golang-google-grpc"},
          {"reference": "google-guest-agent"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "golang-google-grpc"},
          {"reference": "google-guest-agent"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "golang-google-grpc"},
          {"reference": "google-guest-agent"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "golang-google-grpc"},
          {"reference": "google-guest-agent"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "golang-google-grpc"},
          {"reference": "google-guest-agent"}
        ]
      }
    ]
  },
  "Ubuntu Linux-25.10": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "25.10",
        "pkgs": [
          {"reference": "golang-google-grpc"},
          {"reference": "google-guest-agent"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "golang-google-grpc"},
          {"reference": "google-guest-agent"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "ignition"},
          {"reference": "ignition-edge"},
          {"reference": "ignition-grub"},
          {"reference": "ignition-validate"}
        ]
      }
    ]
  },
  "CentOS Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "rhc"},
          {"reference": "rhc-worker-script"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "rhc"},
          {"reference": "rhc-worker-script"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "osbuild-composer"},
          {"reference": "osbuild-composer-core"},
          {"reference": "osbuild-composer-dnf-json"},
          {"reference": "osbuild-composer-worker"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "osbuild-composer"},
          {"reference": "osbuild-composer-core"},
          {"reference": "osbuild-composer-dnf-json"},
          {"reference": "osbuild-composer-worker"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "ignition"}
        ]
      }
    ]
  }
};

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_HOLE,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}