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Linux Distros Unpatched Vulnerability : CVE-2026-84961

🗓️ 04 Sep 2026 00:00:00Reported by TenableType 
nessus
 nessus
🔗 www.tenable.com👁 2 Views

undici BalancedPool JSON deep-clone drops function-valued TLS options, bypassing cert checks.

Related
Refs
Code
ReporterTitlePublishedViews
Family
circl
Circl
CVE-2026-84961
4 Sep 202616:49
circl
cve
CVE
CVE-2026-84961
4 Sep 202616:47
cve
cvelist
Cvelist
CVE-2026-84961 undici vulnerable to TLS certificate validation bypass via dropped connect options in BalancedPool
4 Sep 202616:47
cvelist
debiancve
Debian CVE
CVE-2026-84961
4 Sep 202616:47
debiancve
euvd
EUVD
EUVD-2026-71494
4 Sep 202616:47
euvd
nvd
NVD
CVE-2026-84961
4 Sep 202617:17
nvd
osv
OSV
DEBIAN-CVE-2026-84961
4 Sep 202617:17
osv
ptsecurity
Positive Technologies
PT-2026-85804
4 Sep 202600:00
ptsecurity
redhatcve
RedhatCVE
CVE-2026-84961
4 Sep 202617:46
redhatcve
vulnrichment
Vulnrichment
CVE-2026-84961 undici vulnerable to TLS certificate validation bypass via dropped connect options in BalancedPool
4 Sep 202616:47
vulnrichment
#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(342853);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/04");

  script_cve_id("CVE-2026-84961");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-84961");

  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.

  - undici's BalancedPool constructor passes its entire options object through an internal deep-clone that
    serializes and reparses the value as JSON. Because JSON cannot represent functions, any function-valued
    TLS option, such as a caller-supplied checkServerIdentity callback or a custom connector inside the
    connect option, is silently discarded before it reaches the TLS layer. As a result a peer whose
    certificate the application's custom checkServerIdentity was written to reject, but which still passes
    Node's default hostname and chain checks, is accepted when reached through BalancedPool. The Client, Pool,
    and Agent dispatchers are not affected because they extract the connect and tls options before cloning.
    This affects undici versions from 7.24.1 up to 7.29.1 and from 8.0.0 up to 8.10.2, and only when the
    application supplies a function-valued connect or tls option to BalancedPool. Users should upgrade to
    undici 7.29.1 or 8.10.2. (CVE-2026-84961)

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-2026-84961");
  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:P/I:P/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-84961");

  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:"2026/09/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/04");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:9");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:grafana");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:grafana-selinux");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs-docs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs-full-i18n");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs-nodemon");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs-npm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs-packaging");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs-packaging-bundler");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs22");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs24");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs24-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs24-docs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs24-full-i18n");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs24-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs24-npm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:nodejs26");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:npm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:v8-12.4-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:v8-13.6-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:grafana");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:grafana-selinux");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs-docs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs-full-i18n");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs-nodemon");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs-npm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs-packaging");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs-packaging-bundler");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs22");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs24");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs24-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs24-docs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs24-full-i18n");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs24-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs24-npm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:nodejs26");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:npm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:v8-12.4-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:v8-13.6-devel");
  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-8", "Host/OS/Red Hat Enterprise Linux-10", "Host/OS/Red Hat Enterprise Linux-8", "Host/OS/Red Hat Enterprise Linux-9");

  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/RedHat/rpm-list"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "grafana"},
          {"reference": "grafana-selinux"},
          {"reference": "nodejs"},
          {"reference": "nodejs-devel"},
          {"reference": "nodejs-docs"},
          {"reference": "nodejs-full-i18n"},
          {"reference": "nodejs-libs"},
          {"reference": "nodejs-npm"},
          {"reference": "nodejs22"},
          {"reference": "nodejs24"},
          {"reference": "nodejs24-devel"},
          {"reference": "nodejs24-docs"},
          {"reference": "nodejs24-full-i18n"},
          {"reference": "nodejs24-libs"},
          {"reference": "nodejs24-npm"},
          {"reference": "nodejs26"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "nodejs"},
          {"reference": "nodejs-devel"},
          {"reference": "nodejs-docs"},
          {"reference": "nodejs-full-i18n"},
          {"reference": "nodejs-libs"},
          {"reference": "nodejs-nodemon"},
          {"reference": "nodejs-packaging"},
          {"reference": "nodejs-packaging-bundler"},
          {"reference": "npm"},
          {"reference": "v8-12.4-devel"},
          {"reference": "v8-13.6-devel"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "nodejs"},
          {"reference": "nodejs-devel"},
          {"reference": "nodejs-docs"},
          {"reference": "nodejs-full-i18n"},
          {"reference": "nodejs-libs"},
          {"reference": "nodejs-nodemon"},
          {"reference": "nodejs-packaging"},
          {"reference": "nodejs-packaging-bundler"},
          {"reference": "npm"},
          {"reference": "v8-12.4-devel"},
          {"reference": "v8-13.6-devel"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "nodejs"},
          {"reference": "nodejs-docs"},
          {"reference": "nodejs-full-i18n"},
          {"reference": "nodejs-libs"},
          {"reference": "npm"}
        ]
      }
    ]
  }
};

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');
}

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04 Sep 2026 00:00Current
CVSS 3.17.4
SSVC
2