CVE-2019-25781

Python-Markdown 3.0 through 3.11.2 Denial of Service via Link Bracket Parsing

Published Oct 29, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

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

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 3, 2026, 3:29 PM
Reserved
Oct 29, 2026, 11:51 AM
Status
Awaiting Analysis
Published
Oct 29, 2026, 2:17 PM
Modified
Nov 3, 2026, 4:17 PM
Severity
Important
Public date
Oct 29, 2026, 1:08 PM