lepture Mistune up to 3.2.x HTMLRenderer safe_url HTML injection

CVSS Meta Temp Score
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CTI Interest Score
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4.1$0-$5k0.58+

Summaryinfo

A vulnerability was found in lepture Mistune up to 3.2.x. It has been classified as problematic. Affected by this issue is the function safe_url of the component HTMLRenderer. This manipulation causes HTML injection. This vulnerability is tracked as CVE-2026-59923. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in lepture Mistune up to 3.2.x. It has been declared as problematic. Affected by this vulnerability is the function safe_url of the component HTMLRenderer. The manipulation with an unknown input leads to a html injection vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect integrity. The summary by CVE is:

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, HTMLRenderer.safe_url() does not block percent-encoded javascript URIs, allowing attacker-supplied Markdown links or images to bypass URL protections and execute script in rendered HTML. This issue is fixed in version 3.3.0.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-59923 since 07/07/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 3.3.0 eliminates this vulnerability.

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Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.1

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

CVSSv2info

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

Exploitinginfo

Class: HTML injection
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Upgrade: Mistune 3.3.0

Timelineinfo

07/07/2026 CVE reserved
07/08/2026 +1 days Advisory disclosed
07/08/2026 +0 days VulDB entry created
07/08/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-59923 (🔒)
GCVE (CVE): GCVE-0-2026-59923
GCVE (VulDB): GCVE-100-376927

Entryinfo

Created: 07/08/2026 18:51
Changes: 07/08/2026 18:51 (54)
Complete: 🔍
Cache ID: 216::103

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