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Linux Distros Unpatched Vulnerability : CVE-2026-53262

high Nessus Plugin ID 323405

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

 - l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl() pppol2tp_ioctl() read sock->sk->sk_user_data directly without any locks or reference counting. If a controllable sleep was induced during copy_from_user() (e.g. via a userfaultfd page fault sleep), a concurrent socket close could trigger pppol2tp_session_close() asynchronously. This frees the l2tp_session structure via the l2tp_session_del_work workqueue. Upon resuming, the ioctl thread dereferences the stale session pointer, resulting in a Use-After-Free (UAF). Fix this by securely fetching the session reference using the RCU- safe, refcounted helper pppol2tp_sock_to_session(sk) on entry. This locks the session's refcount across the sleep. We structured the function to exit via standard err breaks, guaranteeing that l2tp_session_put() is cleanly called on all return paths to drop the reference. To preserve existing behavior we validate the session and its magic signature only for the specific L2TP commands that require it. This ensures that generic/unknown ioctls called on an unconnected socket still return -ENOIOCTLCMD and correctly fall back to generic handlers (e.g. in sock_do_ioctl()). (CVE-2026-53262)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

See Also

https://security-tracker.debian.org/tracker/CVE-2026-53262

https://ubuntu.com/security/CVE-2026-53262

Plugin Details

Severity: High

ID: 323405

File Name: unpatched_CVE_2026_53262.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Misc.

Published: 6/28/2026

Updated: 6/28/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 7.2

Temporal Score: 6.1

Vector: CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-53262

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 7.1

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:U/RC:C

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:11.0, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:debian:debian_linux:linux, p-cpe:/a:canonical:ubuntu_linux:linux, p-cpe:/a:canonical:ubuntu_linux:linux-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-aws, p-cpe:/a:canonical:ubuntu_linux:linux-azure, p-cpe:/a:canonical:ubuntu_linux:linux-gcp, p-cpe:/a:canonical:ubuntu_linux:linux-gke, p-cpe:/a:canonical:ubuntu_linux:linux-azure-edge, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-gkeop, p-cpe:/a:canonical:ubuntu_linux:linux-gkeop-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-oracle, p-cpe:/a:canonical:ubuntu_linux:linux-raspi, p-cpe:/a:canonical:ubuntu_linux:linux-oem, p-cpe:/a:canonical:ubuntu_linux:linux-raspi2, p-cpe:/a:canonical:ubuntu_linux:linux-aws-hwe, p-cpe:/a:canonical:ubuntu_linux:linux-bluefield, p-cpe:/a:canonical:ubuntu_linux:linux-ibm, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde, cpe:/o:canonical:ubuntu_linux:14.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.15, cpe:/o:debian:debian_linux:12.0, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-azure-4.15, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-4.15, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-hwe, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-intel-iotg, p-cpe:/a:canonical:ubuntu_linux:linux-intel-iotg-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-iot, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-raspi-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-riscv, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-xilinx-zynqmp, p-cpe:/a:canonical:ubuntu_linux:linux-gkeop-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-edge, p-cpe:/a:canonical:ubuntu_linux:linux-ibm-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-ibm-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-intel-iot-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-lts-xenial, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-lowlatency, p-cpe:/a:canonical:ubuntu_linux:linux-raspi-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.0, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-gke-4.15, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.6, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.0, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-tegra, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-tegra-igx, p-cpe:/a:canonical:ubuntu_linux:linux-allwinner-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-intel-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-azure-nvidia, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-ibm-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-tegra-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.10, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.14, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.17, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.0, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.1, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.11, cpe:/o:canonical:ubuntu_linux:25.10, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-azure-nvidia-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-xilinx, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-6.17, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-7.0, p-cpe:/a:canonical:ubuntu_linux:linux-oem-7.0, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-7.0

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 6/25/2026

Reference Information

CVE: CVE-2026-53262