CVE-2026-59926 | BDVDB-2026-346392 Detail

lepturemistune

Description#

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonition() in src/mistune/directives/admonition.py concatenates the Admonition directive :class: option into the HTML class attribute without escaping, allowing attribute injection and cross-site scripting even when HTMLRenderer escape mode is enabled. This issue is fixed in version 3.2.1.

Impact#

Per CVSS v4.0: confidentiality impact low, integrity impact low, availability impact none. Attack vector: network.

Weaknesses#

CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

References#

Exploit#

No public exploit known

History#

Version 12026-07-08Record published in the CVE List.

Published

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

Vendor information

Vendor: lepture
Product: mistune

All lepture vulnerabilities

Score

5.3 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 26.0.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Cross-Site Scripting

Action

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

Affected Systems

Vulnerable
< 3.2.1
Fixed
Not stated

Scoring System

CVSS v4.0

5.3 Medium

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Attack Requirements	None
Privileges Required	None
User Interaction	Passive
Vulnerable System Confidentiality	Low
Vulnerable System Integrity	Low
Vulnerable System Availability	None
Subsequent System Confidentiality	Low
Subsequent System Integrity	Low
Subsequent System Availability	None

CVSS v3.1

Not available

CVSS v3.0

Not available

CVSS v2

Not available

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