SB20261110254 - Inefficient regular expression complexity in pymdown-extensions

CSH
CYBERSECURITY HELP
Sign In REGISTER

Main Vulnerability Database SB20261110254

SB20261110254 - Inefficient regular expression complexity in pymdown-extensions

Published: November 10, 2026

Security Bulletin ID SB20261110254
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Partial DoS

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: N/A)

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

CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to cause a denial of service through excessive CPU consumption in Markdown rendering.

The vulnerability exists due to inefficient regular expression complexity in pymdownx.critic when processing unclosed CriticMarkup, causing quadratic processing time for ordinary markers and cubic processing time for substitutions. A remote attacker can submit untrusted Markdown containing repeated "{++" or "{~~a~>b" sequences without closing markers to tie up a renderer with the extension enabled for seconds to minutes.


Remediation

Install update from vendor's website.

References