CVE-2026-59922 | BDVDB-2026-346388 Detail

lepturemistune

Description#

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.

Impact#

Per CVSS v3.1: confidentiality impact none, integrity impact none, availability impact high. Attack vector: network.

Weaknesses#

CWE-407 Inefficient Algorithmic Complexity
CWE-1333 Inefficient Regular Expression Complexity

References#

Exploit#

No public exploit known

History#

Version 12026-07-08Record published in the CVE List.
Version 22026-07-09Most recent update recorded in the CVE List.

Published

Published: 2026-07-08
Last modified: 2026-07-09

Vendor information

Vendor: lepture
Product: mistune

All lepture vulnerabilities

Score

7.5 High

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 51.2.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
< 3.3.0
Fixed
Not stated

Scoring System

CVSS v4.0

Not available

CVSS v3.1

7.5 High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	None
User Interaction	None
Scope	Unchanged
Confidentiality	None
Integrity	None
Availability	High

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).