Linux Distros Unpatched Vulnerability : CVE-2026-2391

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

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  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/22");

  script_cve_id("CVE-2026-2391");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-2391");

  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.

  - ### Summary The `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma:
    true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of
    the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p
    (CVE-2025-15284). ### Details When the `comma` option is set to `true` (not the default, but configurable
    in applications), qs allows parsing comma-separated strings as arrays (e.g., `?param=a,b,c` becomes `['a',
    'b', 'c']`). However, the limit check for `arrayLimit` (default: 20) and the optional throwOnLimitExceeded
    occur after the comma-handling logic in `parseArrayValue`, enabling a bypass. This permits creation of
    arbitrarily large arrays from a single parameter, leading to excessive memory allocation. **Vulnerable
    code** (lib/parse.js: lines ~40-50): ```js if (val && typeof val === 'string' && options.comma &&
    val.indexOf(',') > -1) { return val.split(','); } if (options.throwOnLimitExceeded && currentArrayLength
    >= options.arrayLimit) { throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + '
    element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.'); } return val; ``` The
    `split(',')` returns the array immediately, skipping the subsequent limit check. Downstream merging via
    `utils.combine` does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy
    allows attackers to send a single parameter with millions of commas (e.g., `?param=,,,,,,,,...`),
    allocating massive arrays in memory without triggering limits. It bypasses the intent of `arrayLimit`,
    which is enforced correctly for indexed (`a[0]=`) and bracket (`a[]=`) notations (the latter fixed in
    v6.14.1 per GHSA-6rw7-vpxm-498p). ### PoC **Test 1 - Basic bypass:** ``` npm install qs ``` ```js const qs
    = require('qs'); const payload = 'a=' + ','.repeat(25); // 26 elements after split (bypasses arrayLimit:
    5) const options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true }; try { const result =
    qs.parse(payload, options); console.log(result.a.length); // Outputs: 26 (bypass successful) } catch (e) {
    console.log('Limit enforced:', e.message); // Not thrown } ``` **Configuration:** - `comma: true` -
    `arrayLimit: 5` - `throwOnLimitExceeded: true` Expected: Throws Array limit exceeded error. Actual:
    Parses successfully, creating an array of length 26. ### Impact Denial of Service (DoS) via memory
    exhaustion. (CVE-2026-2391)

Note that Nessus relies on the presence of the package as reported by the vendor.");
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  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-2391");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-2391");
  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:POC/RL:U/RC:C");
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  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-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-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-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 = {
  "Debian Linux-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "node-qs"}
        ]
      }
    ]
  },
  "Debian Linux-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "node-qs"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "node-qs"}
        ]
      }
    ]
  },
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "node-qs"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "node-qs"}
        ]
      }
    ]
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  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "node-qs"}
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  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
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        "release": "20.04",
        "pkgs": [
          {"reference": "node-qs"}
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  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "node-qs"}
        ]
      }
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  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "node-qs"}
        ]
      }
    ]
  },
  "Ubuntu Linux-25.10": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "25.10",
        "pkgs": [
          {"reference": "node-qs"}
        ]
      }
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  },
  "Red Hat Enterprise Linux-10": {
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          {"reference": "grafana-stackdriver"},
          {"reference": "mozjs60"},
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  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
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          {"reference": "grafana-mysql"},
          {"reference": "grafana-opentsdb"},
          {"reference": "grafana-postgres"},
          {"reference": "grafana-prometheus"},
          {"reference": "grafana-selinux"},
          {"reference": "grafana-stackdriver"},
          {"reference": "mozjs60"},
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          {"reference": "pcs"},
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  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
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          {"reference": "firefox-x11"},
          {"reference": "gjs"},
          {"reference": "gjs-devel"},
          {"reference": "grafana"},
          {"reference": "grafana-selinux"},
          {"reference": "pcs"},
          {"reference": "pcs-snmp"},
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          {"reference": "polkit-libs"},
          {"reference": "sgx-common"},
          {"reference": "sgx-libs"},
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          {"reference": "tdx-qgs"},
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};

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');
}