lepture mistune up to 3.2.0 Python Markdown Parser HTMLRenderer.heading ID cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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5.1$0-$5k0.00

Summaryinfo

A vulnerability was found in lepture mistune up to 3.2.0 and classified as problematic. Impacted is the function HTMLRenderer.heading of the component Python Markdown Parser. Such manipulation of the argument ID leads to cross site scripting. This vulnerability is referenced as CVE-2026-44897. It is possible to launch the attack remotely. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in lepture mistune up to 3.2.0 and classified as problematic. Affected by this issue is the function HTMLRenderer.heading of the component Python Markdown Parser. The manipulation of the argument id with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. CVE summarizes:

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, HTMLRenderer.heading() builds the opening <hN> tag by string-concatenating the id attribute value directly into the HTML — with no call to escape(), safe_entity(), or any other sanitisation function. A double-quote character " in the id value terminates the attribute, allowing an attacker to inject arbitrary additional attributes (event handlers, src=, href=, etc.) into the heading element. This vulnerability is fixed in 3.2.1.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-44897 since 05/07/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

Upgrading to version 3.2.1 eliminates this vulnerability. The upgrade is hosted for download at github.com.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.2
VulDB Meta Temp Score: 5.1

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.1
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: mistune 3.2.1

Timelineinfo

05/07/2026 CVE reserved
05/26/2026 +19 days Advisory disclosed
05/26/2026 +0 days VulDB entry created
06/01/2026 +6 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-v87v-83h2-53w7
Status: Confirmed

CVE: CVE-2026-44897 (🔒)
GCVE (CVE): GCVE-0-2026-44897
GCVE (VulDB): GCVE-100-365810

Entryinfo

Created: 05/26/2026 23:33
Updated: 06/01/2026 13:44
Changes: 05/26/2026 23:33 (68), 06/01/2026 13:44 (1)
Complete: 🔍
Cache ID: 216::103

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