CVE-2026-59923 — Security Box Score

CVE · referencelatest edition

Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-59923MEDIUM

lepture mistune — Mistune: XSS via percent-encoded javascript URI bypass in safe_url()

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   R  C  L  L  N    6.1   .0024   15.2     —

AFFECTED
  Product  Versions   Fixed
  mistune  < 3.3.0 –  —

TIMELINE
  Jul 7   Reserved by GitHub_M
  Jul 8   EXPLOIT PUBLISHED — CVE-2026-59923 (lepture mistune). Public exploit reference added.
  Jul 8   Published (CNA: GitHub_M)

CWE-79 · CNA: GitHub_M · CVSS v3.1 · 3 references · NVD status: Analyzed

Description

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
July 7, 2026	Reserved	Reserved by GitHub_M
July 8, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-59923 (lepture mistune). Public exploit reference added.
July 8, 2026	Published	Published (CNA: GitHub_M)

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
lepture	mistune	—	< 3.3.0	—

Weaknesses

CWE-79

References (3)

https://github.com/lepture/mistune/commit/c7101fcbb6e8790e8e39157c5ca2238fc6dd6cbc [Patch]
https://github.com/lepture/mistune/releases/tag/v3.3.0 [Release Notes]
https://github.com/lepture/mistune/security/advisories/GHSA-8c25-4j27-2rv3 [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-59923 at cve.org

Vendors: lepture

Weaknesses: CWE-79

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-59923 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.