Python-Markdown 3.0 through 3.11.2 contains an algorithmic complexity vulnerability in inline link parsing that allows remote attackers to exhaust CPU through unmatched brackets. Attackers can submit short Markdown containing repeated [ or ![ characters, forcing LinkInlineProcessor.getText() and getLink() into quadratic scans that keep workers busy for minutes.
History

Tue, 03 Nov 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 30 Oct 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-606
References
Metrics threat_severity

None

threat_severity

Important


Fri, 30 Oct 2026 06:45:00 +0000

Type Values Removed Values Added
First Time appeared Python-markdown
Python-markdown markdown
Vendors & Products Python-markdown
Python-markdown markdown

Thu, 29 Oct 2026 13:30:00 +0000

Type Values Removed Values Added
Description Python-Markdown 3.0 through 3.11.2 contains an algorithmic complexity vulnerability in inline link parsing that allows remote attackers to exhaust CPU through unmatched brackets. Attackers can submit short Markdown containing repeated [ or ![ characters, forcing LinkInlineProcessor.getText() and getLink() into quadratic scans that keep workers busy for minutes.
Title Python-Markdown 3.0 through 3.11.2 Denial of Service via Link Bracket Parsing
First Time appeared Python-markdown2 Project
Python-markdown2 Project python-markdown2
Weaknesses CWE-407
CPEs cpe:2.3:a:python-markdown2_project:python-markdown2:*:*:*:*:*:*:*:*
Vendors & Products Python-markdown2 Project
Python-markdown2 Project python-markdown2
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': '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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-10-29T13:08:49.597Z

Updated: 2026-11-03T15:29:33.399Z

Reserved: 2026-10-29T11:51:49.648Z

Link: CVE-2019-25781

cve-icon Vulnrichment

Updated: 2026-11-03T15:29:27.751Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-29T14:17:39.170

Modified: 2026-11-03T16:17:15.607

Link: CVE-2019-25781

cve-icon Redhat

Severity : Important

Publid Date: 2026-10-29T13:08:49Z

Links: CVE-2019-25781 - Bugzilla