SB20261109106 - Inefficient Algorithmic Complexity in pymdown-extensions

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Main Vulnerability Database SB20261109106

SB20261109106 - Inefficient Algorithmic Complexity in pymdown-extensions

Published: November 9, 2026

Security Bulletin ID SB20261109106
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 Algorithmic Complexity (CVE-ID: N/A)

CWE-ID: CWE-407 - Inefficient Algorithmic 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 an unauthenticated remote attacker to degrade rendering worker availability through excessive CPU consumption.

The vulnerability exists due to quadratic-time rescanning of uninterrupted delimiter runs in pymdown-extensions when rendering untrusted Markdown with pymdownx.caret, pymdownx.tilde, or pymdownx.mark enabled. An unauthenticated remote attacker can submit a request containing tens of kilobytes of repeated delimiters to occupy a render worker for seconds without victim interaction.


Remediation

Install update from vendor's website.

References