What is CVE-2026-59929?

CVE-2026-59929 is a medium-severity vulnerability in Lepture Mistune, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-07-08.

How severe is CVE-2026-59929?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Lepture Mistune

CVE-2026-59929

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safe_url filter in src/mistune/renderers/html.py blocks only javascript:, vbscript:, file:, and data: schemes, allowing legacy or chained schemes such as f…

Vulnerability class: XSS (Cross-Site Scripting)

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Lepture Mistune — versions < 3.3.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting
CWE-184 — Incomplete List of Disallowed Inputs

References

security-advisories@github.com (x_refsource_CONFIRM)
security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-59929?: CVE-2026-59929 is a medium-severity vulnerability in Lepture Mistune, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-07-08.
How severe is CVE-2026-59929?: Medium severity. CVSS v3 base score is 6.1 out of 10.