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,...

GHSA-G97X-GVCM-X72H Mistune: XSS via unescaped class option in Admonition directive

In src/mistune/directives/admonition.py, the renderadmonition function concatenates the :class: option directly into the HTML class attribute without escaping lines 63-68. This allows attribute injection and XSS even when HTMLRendererescape=True is used. The directive name parameter is safe...

GHSA-8C25-4J27-2RV3 Mistune: XSS via percent-encoded javascript URI bypass in safe_url()

Summary An XSS vulnerability in Mistune allows bypassing of safeurl protections via percent-encoded javascript URIs. Details The vulnerability exists in HTMLRenderer.safeurl in Mistune. The function is intended to block harmful URL schemes such as "javascript:" by checking the prefix of the...

CVE-2026-44897

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, HTMLRenderer.heading builds the opening tag by string-concatenating the id attribute value directly into the HTML — with no call to escape, safeentity, or any other sanitisation function. A double-quote character " in...

Cross-site Scripting (XSS)

Overview Affected versions of this package are vulnerable to Cross-site Scripting XSS via the HTMLRenderer heading rendering path in the HTML renderer. An attacker can inject arbitrary HTML by supplying a heading id attribute value that contains quotes and markup. The rendered output can be alter...

GHSA-V87V-83H2-53W7 Mistune Heading ID Attribute has Injection XSS

Summary HTMLRenderer.heading builds the opening tag by string-concatenating the id attribute value directly into the HTML — with no call to escape, safeentity, or any other sanitisation function. A double-quote character " in the id value terminates the attribute, allowing an attacker to inject...

MAL-2024-1579 Malicious code in mmsdk-apml-htmlrenderer (npm)

--- -= Per source details. Do not edit below this line.=- Source: ghsa-malware ae0814f13d1d5f49711b30a6fe260c2bfb566047df1b02774e899421faf58c92 Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be...

Malicious code in mmsdk-apml-htmlrenderer (npm)

--- -= Per source details. Do not edit below this line.=- Source: ghsa-malware ae0814f13d1d5f49711b30a6fe260c2bfb566047df1b02774e899421faf58c92 Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be...