CVE-2026-8445
justhtml versions <= 1.11.0 (fixed in 1.12.0) do not sufficiently escape HTML-significant characters (angle brackets) in text nodes when converting a parsed document to Markdown via to_markdown(). While a small set of Markdown metacharacters are escaped, characters such as < and > are preserved, so untrusted input that is safe in to_html() — including entity-decoded text (e.g. <script>) or text from RCDATA/RAWTEXT-parsed elements like <title>, <textarea>, <noscript>, and <plaintext> — can be emitted as raw HTML in the Markdown output, enabling a sanitizer bypass and potential cross-site scripting when that output is rendered.
- Score
- CVSS 3.1 9.8 Critical
- Status
- Deferred - disclosure@vulncheck.com
- Published
- 2026-08-23
- Last modified
- 2026-10-12
- Weaknesses
- CWE-79
Affected products
References
- https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-3rcm-vjrc-p45j
- https://www.vulncheck.com/advisories/justhtml-before-sanitizer-bypass-via-markdown
