justhtml before 1.12.0 Sanitizer Bypass via Markdown (CVE-2026-8445) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-8445

justhtml before 1.12.0 Sanitizer Bypass via Markdown

Answer in brief

CVE-2026-8445 records a Unknown severity vulnerability in justhtml before 1.12.0 Sanitizer Bypass via Markdown. The current sources do not mark it as known exploited. The current feed maps EmilStenstrom/justhtml (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 23, 2026Updated Aug 23, 2026Source checked Aug 23, 2026First seen by HOL Aug 23, 2026Material review Aug 23, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps EmilStenstrom/justhtml (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
EmilStenstrom/justhtmlgeneric	>=0 <1.12.0	1.12.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for EmilStenstrom/justhtml.
Review the reported fix. Update EmilStenstrom/justhtml to 1.12.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 23, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.