HTML Injection Vulnerability in Mistune Markdown Parser by Lepture
CVE-2026-44898

6.1MEDIUM

Key Information:

Vendor

Lepture

Status
Mistune
Vendor
CVE Published:
26 May 2026

What is CVE-2026-44898?

Mistune, a Markdown parser for Python, has a vulnerability in prior versions 3.2.1 that allows an attacker to inject arbitrary HTML tags, including elements, into the rendered table of contents. This issue arises because the render_toc_ul() function does not properly escape user-supplied heading text, leading to the possibility of breaking out of the href attribute context. To mitigate this risk, it is crucial to ensure that Mistune is updated to version 3.2.1 or later.

Affected Version(s)

mistune < 3.2.1

References

https://github.com/lepture/mistune/security/advisories/GH...
x_refsource_CONFIRM
https://github.com/lepture/mistune/releases/tag/v3.2.1
x_refsource_MISC

CVSS V3.1

Score:
6.1
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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