Linux Distros Unpatched Vulnerability : CVE-2026-67422

high Nessus Plugin ID 333354

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.

- pymdown-extensions is a collection of extensions for the Python Markdown library. In versions up to and including 11.0, four inline processors (caret, tilde, betterem, and magiclink) use regular expressions whose content groups can partition a run of delimiter characters in exponentially many ways, causing catastrophic backtracking. As a result, a single untrusted Markdown line under 50 bytes rendered with markdown.markdown() in each extension's default configuration drives the rendering thread into unbounded CPU usage that grows exponentially with input length, enabling an unauthenticated remote attacker who can submit Markdown to cause denial of service. The exposure is concrete for web applications that render user-supplied Markdown (comments, wikis, issue bodies, live preview), including any app using pymdownx.extra which bundles the vulnerable betterem default, as well as hosted docs/CI systems that build untrusted Markdown. The issue has been fixed in version 11.0.1. (CVE-2026-67422)

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

Solution

There is no known solution at this time.

Plugin Details

Severity: High

ID: 333354

File Name: unpatched_CVE_2026_67422.nasl

Version: 1.2

Type: Local

Agent: unix

Family: Misc.

Published: 8/7/2026

Updated: 8/7/2026

Supported Sensors: Agentless Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Frictionless Assessment Azure, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.75

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 4.3

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

CVSS Score Source: CVE-2026-67422

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.9

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

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:14.04:-:lts, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, cpe:/o:debian:debian_linux:12.0, cpe:/o:debian:debian_linux:13.0, p-cpe:/a:canonical:ubuntu_linux:markdown, p-cpe:/a:canonical:ubuntu_linux:python2.7, p-cpe:/a:canonical:ubuntu_linux:python3.10, p-cpe:/a:canonical:ubuntu_linux:python3.11, p-cpe:/a:canonical:ubuntu_linux:python3.12, p-cpe:/a:canonical:ubuntu_linux:python3.14, p-cpe:/a:canonical:ubuntu_linux:python3.4, p-cpe:/a:canonical:ubuntu_linux:python3.5, p-cpe:/a:canonical:ubuntu_linux:python3.6, p-cpe:/a:canonical:ubuntu_linux:python3.7, p-cpe:/a:canonical:ubuntu_linux:python3.8, p-cpe:/a:canonical:ubuntu_linux:python3.9, p-cpe:/a:debian:debian_linux:pymdown-extensions

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

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 8/6/2026

Reference Information

CVE: CVE-2026-67422

Detections

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