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BREW-adr-viewer-CVE-2026-44897 — Mistune Heading ID Attribute has Injection XSS

Affected: Homebrew: adr-viewer

## Summary `HTMLRenderer.heading()` builds the opening `<hN>` tag by string-concatenating the `id` attribute value directly into the HTML — with no call to `escape()`, `safe_entity()`, or any other sanitisation function. A double-quote character `"` in the `id` value terminates the attribute, allowing an attacker to inject arbitrary additional attributes (event handlers, `src=`, `href=`, etc.) into the heading element.

The default TOC hook assigns safe auto-incremented IDs (`toc_1`, `toc_2`, …) that never contain user text. However, the `add_toc_hook()` API accepts a caller-supplied `heading_id` callback. Deriving heading IDs from the heading text itself — to produce human-readable slug anchors like `#installation` or `#getting-started` — is by far the most common real-world usage of this callback (every major documentation generator does this). When the callback returns raw heading text, an attacker who controls heading content can break out of the `id=` attribute.

## Details **File:** `src/mistune/renderers/html.py`

```python def heading(self, text: str, level: int, **attrs: Any) -> str: tag = "h" + str(level) html = "<" + tag _id = attrs.get("id") if _id: html += ' id="' + _id + '"' # ← _id is never escaped return html + ">" + text + "</" + tag + ">\n" ```

The `text` body (line content) *is* escaped upstream by the inline token renderer, which is why `text` arrives as `"` etc. But `_id` arrives as a raw string directly from whatever…

CLEANSTART-2026-DO33300 — Security fix for CVE-2026-44897 applied in: tensorflow-gpu-jupyter 2.21.0-r5

Affected: CleanStart: tensorflow-gpu-jupyter

Security vulnerability affects the tensorflow-gpu-jupyter package. This issue is resolved in later releases. See references for vulnerability details.

EUVD-2026-323535

fkie_cve-2026-44897

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, HTMLRenderer.heading() builds the opening <hN> tag by string-concatenating the id attribute value directly into the HTML — with no call to escape(), safe_entity(), or any other sanitisation function. A double-quote character " in the id value terminates the attribute, allowing an attacker to inject arbitrary additional attributes (event handlers, src=, href=, etc.) into the heading element. This vulnerability is fixed in 3.2.1.

GHSA-v87v-83h2-53w7 — Mistune Heading ID Attribute has Injection XSS

Affected: PyPI: mistune

## Details **File:** `src/mistune/renderers/html.py`

The `text` body (line content) *is* escaped upstream by the inline token renderer, which is why `text` arrives as `"` etc. But `_id` arrives as a raw string directly from whatever…

msrc_CVE-2026-44897 — Mistune Heading ID Attribute Injection XSS

msrc_CVE-2026-44897

openSUSE-SU-2026:10761-1 — python311-mistune-3.2.1-1.1 on GA media

python311-mistune-3.2.1-1.1 on GA media

PYSEC-2026-2207

Affected: PyPI: mistune

SUSE-SU-2026:21858-1 — Security update for python-mistune

Security update for python-mistune

UBUNTU-CVE-2026-44897

Affected: Ubuntu:16.04:LTS: mistune, Ubuntu:18.04:LTS: mistune, Ubuntu:20.04:LTS: mistune, Ubuntu:22.04:LTS: mistune, Ubuntu:22.04:LTS: mistune0, Ubuntu:24.04:LTS: mistune, Ubuntu:24.04:LTS: mistune0, Ubuntu:25.10: mistune, Ubuntu:25.10: mistune0, Ubuntu:26.04:LTS: mistune and 1 more