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Linux Distros Unpatched Vulnerability : CVE-2026-68956

🗓️ 23 Sep 2026 00:00:00Reported by TenableType 
nessus
 nessus🔗 www.tenable.com👁 1 Views

Authenticated remote memory exhaustion in Erlang/OTP ssh via unhandled session channels.

Related
Refs
Code
ReporterTitlePublishedViews
Family
cve
CVE		CVE-2026-68956
22 Sep 202608:49
–cve
cvelist
Cvelist		CVE-2026-68956 SSH daemon allocates unbounded idle session channels, bypassing max_channels
22 Sep 202608:49
–cvelist
debiancve
Debian CVE		CVE-2026-68956
22 Sep 202608:49
–debiancve
euvd
EUVD		EUVD-2026-84339
22 Sep 202608:49
–euvd
mscve
Microsoft CVE		SSH daemon allocates unbounded idle session channels, bypassing max_channels
24 Sep 202608:45
–mscve
nvd
NVD		CVE-2026-68956
22 Sep 202609:17
–nvd
osv
OSV		AZL-103425 CVE-2026-68956 affecting package erlang 26.2.5.21-6
22 Sep 202609:17
–osv
osv
OSV		CVE-2026-68956 SSH daemon allocates unbounded idle session channels, bypassing max_channels
22 Sep 202608:49
–osv
osv
OSV		DEBIAN-CVE-2026-68956
22 Sep 202609:17
–osv
osv
OSV		EEF-CVE-2026-68956 SSH daemon allocates unbounded idle session channels, bypassing max_channels
22 Sep 202608:49
–osv
Rows per page
#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(349175);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/23");

  script_cve_id("CVE-2026-68956");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-68956");

  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.

  - Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an
    authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never
    assigned a handler. The session clause of ssh_connection:handle_msg/4 checks only
    minimal_remote_max_packet_size before calling setup_session/5, which unconditionally builds a #channel{}
    record and stores it in the ETS channel cache. The max_channels daemon option is consulted only by
    ssh_channel_sup:max_num_channels_not_exceeded/2, which counts supervisor children, so a channel that never
    gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite
    value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and
    each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels
    until the node runs out of memory and the emulator terminates, affecting every application on it. No file
    contents, credentials, or write access are obtainable. This issue affects OTP from OTP 18.1.2 before OTP
    27.3.4.18, OTP 28.5.0.7, and OTP 29.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and
    6.0.6. Whether OTP before OTP 18.1.2, corresponding to ssh before 4.1.1, is affected is unknown.
    (CVE-2026-68956)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-68956");
  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:S/C:N/I:N/A:C");
  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:L/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:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-68956");

  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:"2026/09/22");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/23");

  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:"p-cpe:/a:canonical:ubuntu_linux:erlang");
  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/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 = {
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-appmon"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-base-hipe"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-corba"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-dbg"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-gs"},
          {"reference": "erlang-ic"},
          {"reference": "erlang-ic-java"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-percept"},
          {"reference": "erlang-pman"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-test-server"},
          {"reference": "erlang-toolbar"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-tv"},
          {"reference": "erlang-typer"},
          {"reference": "erlang-webtool"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-base-hipe"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-corba"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-dbg"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-gs"},
          {"reference": "erlang-ic"},
          {"reference": "erlang-ic-java"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-percept"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-test-server"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-typer"},
          {"reference": "erlang-webtool"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-base-hipe"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-corba"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ic"},
          {"reference": "erlang-ic-java"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-base-hipe"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ftp"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tftp"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ftp"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tftp"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ftp"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tftp"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ftp"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tftp"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  }
};

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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23 Sep 2026 00:00Current
5.9Medium risk
Vulners AI Score5.9
CVSS 47.1
EPSS0.00664
SSVC
Erlang/OTPsshmemory exhaustionauthenticated remote attackssh_connection:handle_msg/4
1