SB2026080391 - Inefficient regular expression complexity in pymdown-extensions

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Main Vulnerability Database SB2026080391

SB2026080391 - Inefficient regular expression complexity in pymdown-extensions

Published: August 3, 2026

Security Bulletin ID SB2026080391
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Denial of service

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Inefficient regular expression complexity (CVE-ID: CVE-2026-67422)

CWE-ID: CWE-1333 - Inefficient Regular Expression Complexity

CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to inefficient regular expression complexity in the caret, tilde, betterem, and magiclink inline processors when rendering untrusted Markdown input through the public API in the default configuration. A remote attacker can submit a specially crafted Markdown line to cause a denial of service.

A single untrusted Markdown line under 50 bytes can drive the rendering thread into unbounded CPU usage.


Remediation

Install update from vendor's website.

References