XSS Vulnerability in Mistune Python Markdown Parser
CVE-2026-44896

5.3MEDIUM

Key Information:

Vendor

Lepture

Status
Mistune
Vendor
CVE Published:
26 May 2026

What is CVE-2026-44896?

The Mistune Markdown parser allows attackers to exploit a vulnerability in its handling of HTML attributes. Specifically, in versions 3.2.0 and earlier, the render_figure() function does not adequately escape figclass and figwidth inputs. This flaw permits the injection of malicious attributes, leading to an XSS vulnerability even when the HTMLRenderer is configured to escape HTML. Proper validation and escaping measures are needed to mitigate this risk.

Affected Version(s)

mistune <= 3.2.0

References

https://github.com/lepture/mistune/security/advisories/GH...
x_refsource_CONFIRM

CVSS V4

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.