GHSA-QFRW-5RXM-MHH2 Mistune renderers/html.safe_url: HARMFUL_PROTOCOLS list misses legacy and chained schemes that historically chain to `javascript:` execution

Summary Type: URL-scheme allowlist gap. The safeurl filter only blocks the four schemes javascript:, vbscript:, file:, data:. Several other schemes are accepted into rendered and tags despite being known XSS vectors in legacy or chain-handling browsers. The same gap applies to direct links,...

CVE-2026-59929

A flaw was found in Mistune, a Python Markdown parser. The safeurl filter, intended to prevent malicious Uniform Resource Locators URLs, did not adequately block all potentially harmful schemes. This oversight allows an attacker to embed specially crafted URLs using legacy or chained schemes with...

Cross-site Scripting (XSS)

Overview Affected versions of this package are vulnerable to Cross-site Scripting XSS via the safeurl function. An attacker can execute arbitrary scripts in the rendered HTML by supplying specially crafted percent-encoded javascript URIs in Markdown links or images. Details Cross-site scripting o...

CVE-2026-59929

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safeurl filter in src/mistune/renderers/html.py blocks only javascript:, vbscript:, file:, and data: schemes, allowing legacy or chained schemes such as feed:, view-source:, jar:, livescript:, mocha:, ms-its:, mk:...

CVE-2026-59929 Mistune renderers/html.safe_url: HARMFUL_PROTOCOLS list misses legacy and chained schemes that historically chain to `javascript:` execution

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safeurl filter in src/mistune/renderers/html.py blocks only javascript:, vbscript:, file:, and data: schemes, allowing legacy or chained schemes such as feed:, view-source:, jar:, livescript:, mocha:, ms-its:, mk:...

CVE-2026-59929

Mistune is a Python Markdown parser. CVE-2026-59929 affects the safe_url filter in src/mistune/renderers/html.py prior to version 3.3.0, which blocks only javascript:, vbscript:, file:, and data: schemes. This allowed legacy or chained schemes such as feed:, view-source:, jar:, livescript:, mocha...

CVE-2013-6044

The issafeurl function in utils/http.py in Django 1.4.x before 1.4.6, 1.5.x before 1.5.2, and 1.6 before beta 2 treats a URL's scheme as safe even if it is not HTTP or HTTPS, which might introduce cross-site scripting XSS or other vulnerabilities into Django applications that use this function, a...