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Linux Distros Unpatched Vulnerability : CVE-2026-42772

🗓️ 29 Sep 2026 00:00:00Reported by TenableType 
nessus
 nessus
🔗 www.tenable.com👁 1 Views

Inefficient algorithmic complexity in OpenSSL QUIC stream reassembly enables DoS.

Related
Refs
Code
ReporterTitlePublishedViews
Family
freebsd
FreeBSD
OpenSSL -- Multiple vulnerabilities
29 Sep 202600:00
–freebsd
circl
Circl
CVE-2026-42772
29 Sep 202619:46
–circl
cve
CVE
CVE-2026-42772
29 Sep 202615:32
–cve
cvelist
Cvelist
CVE-2026-42772 Potential CPU DoS via O(n^2) Fragment Reassembly in QUIC
29 Sep 202615:32
–cvelist
debian
Debian
[SECURITY] [DSA 6531-1] openssl security update
30 Sep 202606:09
–debian
debiancve
Debian CVE
CVE-2026-42772
29 Sep 202615:32
–debiancve
nessus
Tenable Nessus
Debian dsa-6531 : libcrypto3-udeb - security update
30 Sep 202600:00
–nessus
euvd
EUVD
EUVD-2026-89003
29 Sep 202615:32
–euvd
nvd
NVD
CVE-2026-42772
29 Sep 202616:17
–nvd
openssl
OpenSSL
Potential CPU DoS via O(n^2) Fragment Reassembly in QUIC
29 Sep 202600:00
–openssl
Rows per page
#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(351205);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/30");

  script_cve_id("CVE-2026-42772");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-42772");

  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.

  - Issue summary: The QUIC stream reassembly algorithm performance deteriorates progressively as packets are
    arriving out of order. The worst case has a quadratic complexity proportional to the number of stream
    frames kept in the buffer for the received stream data. Impact summary: A remote QUIC peer that completes
    the handshake can create a connection-scoped CPU pressure and potentially a Denial of Service using
    compliant STREAM frames inside the advertised receive window, with low attacker bandwidth. CWE: CWE-407:
    Inefficient Algorithmic Complexity Description: OpenSSL manages received QUIC stream fragments using a
    doubly-linked list. While it optimizes for append operations (at the end of the list), it falls back to a
    head-to-tail linear search for any fragment that does not immediately follow the current `tail`. By
    manipulating the sequence of offsets, an attacker can force the server to perform O(n^2) operations,
    consuming excessive CPU time for the QUIC process. FIPS impact: no The FIPS module is not affected as the
    QUIC implementation is outside of the OpenSSL FIPS module boundary. (CVE-2026-42772)

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-2026-42772");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-42772");
  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-2026-42772");

  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:"2026/09/29");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/29");

  script_set_attribute(attribute:"plugin_type", value:"local");
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  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:14.0");
  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:centos:centos:AAVMF");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:OVMF");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:compat-openssl10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:compat-openssl11");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2-aarch64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2-ovmf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:edk2-tools-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:mingw-openssl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:mingw32-openssl");
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  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:mokutil");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:openssl");
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  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:openssl-static");
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  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-7", "Host/OS/CentOS Linux-8", "Host/OS/Debian Linux-14", "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");

  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-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "libcrypto3-udeb"},
          {"reference": "libssl-dev"},
          {"reference": "libssl-doc"},
          {"reference": "libssl3-udeb"},
          {"reference": "libssl3t64"},
          {"reference": "openssl"},
          {"reference": "openssl-provider-fips"},
          {"reference": "openssl-provider-legacy"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "edk2"},
          {"reference": "edk2-aarch64"},
          {"reference": "edk2-ovmf"},
          {"reference": "edk2-tools"},
          {"reference": "edk2-tools-doc"},
          {"reference": "mokutil"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "shim-aa64"},
          {"reference": "shim-unsigned-aarch64"},
          {"reference": "shim-unsigned-x64"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  },
  "CentOS Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "AAVMF"},
          {"reference": "OVMF"},
          {"reference": "mokutil"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "openssl-static"},
          {"reference": "ovmf"},
          {"reference": "shim"},
          {"reference": "shim-ia32"},
          {"reference": "shim-signed"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "AAVMF"},
          {"reference": "OVMF"},
          {"reference": "mokutil"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "openssl-static"},
          {"reference": "ovmf"},
          {"reference": "shim"},
          {"reference": "shim-ia32"},
          {"reference": "shim-signed"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "compat-openssl10"},
          {"reference": "edk2"},
          {"reference": "edk2-aarch64"},
          {"reference": "edk2-ovmf"},
          {"reference": "mingw-openssl"},
          {"reference": "mingw32-openssl"},
          {"reference": "mingw64-openssl"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "openssl-static"},
          {"reference": "shim"},
          {"reference": "shim-aa64"},
          {"reference": "shim-ia32"},
          {"reference": "shim-unsigned-aarch64"},
          {"reference": "shim-unsigned-x64"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "compat-openssl10"},
          {"reference": "edk2"},
          {"reference": "edk2-aarch64"},
          {"reference": "edk2-ovmf"},
          {"reference": "mingw-openssl"},
          {"reference": "mingw32-openssl"},
          {"reference": "mingw64-openssl"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "openssl-static"},
          {"reference": "shim"},
          {"reference": "shim-aa64"},
          {"reference": "shim-ia32"},
          {"reference": "shim-unsigned-aarch64"},
          {"reference": "shim-unsigned-x64"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "compat-openssl11"},
          {"reference": "edk2"},
          {"reference": "edk2-aarch64"},
          {"reference": "edk2-ovmf"},
          {"reference": "edk2-tools"},
          {"reference": "edk2-tools-doc"},
          {"reference": "openssl"},
          {"reference": "openssl-devel"},
          {"reference": "openssl-libs"},
          {"reference": "openssl-perl"},
          {"reference": "shim"},
          {"reference": "shim-aa64"},
          {"reference": "shim-unsigned-aarch64"},
          {"reference": "shim-unsigned-x64"},
          {"reference": "shim-x64"}
        ]
      }
    ]
  }
};

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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30 Sep 2026 00:00Current
6.1Medium risk
Vulners AI Score6.1
CVSS 3.15.3
EPSS0.00166
SSVC
1