Linux Distros Unpatched Vulnerability : CVE-2026-67422

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

include('compat.inc');

if (description)
{
  script_id(333354);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/07");

  script_cve_id("CVE-2026-67422");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-67422");

  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.

  - pymdown-extensions is a collection of extensions for the Python Markdown library. In versions up to and
    including 11.0, four inline processors (caret, tilde, betterem, and magiclink) use regular expressions
    whose content groups can partition a run of delimiter characters in exponentially many ways, causing
    catastrophic backtracking. As a result, a single untrusted Markdown line under 50 bytes rendered with
    markdown.markdown() in each extension's default configuration drives the rendering thread into unbounded
    CPU usage that grows exponentially with input length, enabling an unauthenticated remote attacker who can
    submit Markdown to cause denial of service. The exposure is concrete for web applications that render
    user-supplied Markdown (comments, wikis, issue bodies, live preview), including any app using
    pymdownx.extra which bundles the vulnerable betterem default, as well as hosted docs/CI systems that build
    untrusted Markdown. The issue has been fixed in version 11.0.1. (CVE-2026-67422)

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-2026-67422");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-67422");
  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: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:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-67422");

  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:"2026/08/06");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/07");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  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:26.04:-:lts");
  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:"p-cpe:/a:canonical:ubuntu_linux:markdown");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python2.7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.11");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.12");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.14");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.4");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.5");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.6");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.9");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:pymdown-extensions");
  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/Ubuntu Linux-14.04", "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-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/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": "python3-pymdownx"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "python3-pymdownx"}
        ]
      }
    ]
  },
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "idle-python2.7"},
          {"reference": "idle-python3.4"},
          {"reference": "libpython2.7"},
          {"reference": "libpython2.7-dbg"},
          {"reference": "libpython2.7-dev"},
          {"reference": "libpython2.7-minimal"},
          {"reference": "libpython2.7-stdlib"},
          {"reference": "libpython2.7-testsuite"},
          {"reference": "libpython3.4"},
          {"reference": "libpython3.4-dbg"},
          {"reference": "libpython3.4-dev"},
          {"reference": "libpython3.4-minimal"},
          {"reference": "libpython3.4-stdlib"},
          {"reference": "libpython3.4-testsuite"},
          {"reference": "python2.7"},
          {"reference": "python2.7-dbg"},
          {"reference": "python2.7-dev"},
          {"reference": "python2.7-doc"},
          {"reference": "python2.7-examples"},
          {"reference": "python2.7-minimal"},
          {"reference": "python3.4"},
          {"reference": "python3.4-dbg"},
          {"reference": "python3.4-dev"},
          {"reference": "python3.4-doc"},
          {"reference": "python3.4-examples"},
          {"reference": "python3.4-minimal"},
          {"reference": "python3.5"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "idle-python2.7"},
          {"reference": "idle-python3.5"},
          {"reference": "libpython2.7"},
          {"reference": "libpython2.7-dbg"},
          {"reference": "libpython2.7-dev"},
          {"reference": "libpython2.7-minimal"},
          {"reference": "libpython2.7-stdlib"},
          {"reference": "libpython2.7-testsuite"},
          {"reference": "libpython3.5"},
          {"reference": "libpython3.5-dbg"},
          {"reference": "libpython3.5-dev"},
          {"reference": "libpython3.5-minimal"},
          {"reference": "libpython3.5-stdlib"},
          {"reference": "libpython3.5-testsuite"},
          {"reference": "markdown"},
          {"reference": "python2.7"},
          {"reference": "python2.7-dbg"},
          {"reference": "python2.7-dev"},
          {"reference": "python2.7-doc"},
          {"reference": "python2.7-examples"},
          {"reference": "python2.7-minimal"},
          {"reference": "python3.5"},
          {"reference": "python3.5-dbg"},
          {"reference": "python3.5-dev"},
          {"reference": "python3.5-doc"},
          {"reference": "python3.5-examples"},
          {"reference": "python3.5-minimal"},
          {"reference": "python3.5-venv"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "idle-python2.7"},
          {"reference": "idle-python3.6"},
          {"reference": "libpython2.7"},
          {"reference": "libpython2.7-dbg"},
          {"reference": "libpython2.7-dev"},
          {"reference": "libpython2.7-minimal"},
          {"reference": "libpython2.7-stdlib"},
          {"reference": "libpython2.7-testsuite"},
          {"reference": "libpython3.6"},
          {"reference": "libpython3.6-dbg"},
          {"reference": "libpython3.6-dev"},
          {"reference": "libpython3.6-minimal"},
          {"reference": "libpython3.6-stdlib"},
          {"reference": "libpython3.6-testsuite"},
          {"reference": "markdown"},
          {"reference": "python2.7"},
          {"reference": "python2.7-dbg"},
          {"reference": "python2.7-dev"},
          {"reference": "python2.7-doc"},
          {"reference": "python2.7-examples"},
          {"reference": "python2.7-minimal"},
          {"reference": "python3.6"},
          {"reference": "python3.6-dbg"},
          {"reference": "python3.6-dev"},
          {"reference": "python3.6-doc"},
          {"reference": "python3.6-examples"},
          {"reference": "python3.6-minimal"},
          {"reference": "python3.6-venv"},
          {"reference": "python3.7"},
          {"reference": "python3.8"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "idle-python3.8"},
          {"reference": "libpython3.8"},
          {"reference": "libpython3.8-dbg"},
          {"reference": "libpython3.8-dev"},
          {"reference": "libpython3.8-minimal"},
          {"reference": "libpython3.8-stdlib"},
          {"reference": "libpython3.8-testsuite"},
          {"reference": "markdown"},
          {"reference": "python2.7"},
          {"reference": "python3.8"},
          {"reference": "python3.8-dbg"},
          {"reference": "python3.8-dev"},
          {"reference": "python3.8-doc"},
          {"reference": "python3.8-examples"},
          {"reference": "python3.8-minimal"},
          {"reference": "python3.8-venv"},
          {"reference": "python3.9"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "idle-python3.10"},
          {"reference": "libpython3.10"},
          {"reference": "libpython3.10-dbg"},
          {"reference": "libpython3.10-dev"},
          {"reference": "libpython3.10-minimal"},
          {"reference": "libpython3.10-stdlib"},
          {"reference": "libpython3.10-testsuite"},
          {"reference": "markdown"},
          {"reference": "python2.7"},
          {"reference": "python3.10"},
          {"reference": "python3.10-dbg"},
          {"reference": "python3.10-dev"},
          {"reference": "python3.10-doc"},
          {"reference": "python3.10-examples"},
          {"reference": "python3.10-full"},
          {"reference": "python3.10-minimal"},
          {"reference": "python3.10-nopie"},
          {"reference": "python3.10-venv"},
          {"reference": "python3.11"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "idle-python3.12"},
          {"reference": "libpython3.12-dev"},
          {"reference": "libpython3.12-minimal"},
          {"reference": "libpython3.12-stdlib"},
          {"reference": "libpython3.12-testsuite"},
          {"reference": "libpython3.12t64"},
          {"reference": "libpython3.12t64-dbg"},
          {"reference": "markdown"},
          {"reference": "python3.12"},
          {"reference": "python3.12-dbg"},
          {"reference": "python3.12-dev"},
          {"reference": "python3.12-doc"},
          {"reference": "python3.12-examples"},
          {"reference": "python3.12-full"},
          {"reference": "python3.12-minimal"},
          {"reference": "python3.12-nopie"},
          {"reference": "python3.12-venv"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "idle-python3.14"},
          {"reference": "libpython3.14"},
          {"reference": "libpython3.14-dbg"},
          {"reference": "libpython3.14-dev"},
          {"reference": "libpython3.14-minimal"},
          {"reference": "libpython3.14-stdlib"},
          {"reference": "libpython3.14-testsuite"},
          {"reference": "markdown"},
          {"reference": "python3.14"},
          {"reference": "python3.14-dbg"},
          {"reference": "python3.14-dev"},
          {"reference": "python3.14-doc"},
          {"reference": "python3.14-examples"},
          {"reference": "python3.14-full"},
          {"reference": "python3.14-gdbm"},
          {"reference": "python3.14-minimal"},
          {"reference": "python3.14-nopie"},
          {"reference": "python3.14-tk"},
          {"reference": "python3.14-venv"}
        ]
      }
    ]
  }
};

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');
}