justhtml before 1.12.0 Mutation XSS via Raw Text Elements (CVE-2026-8630) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-8630

justhtml before 1.12.0 Mutation XSS via Raw Text Elements

Answer in brief

CVE-2026-8630 records a Unknown severity vulnerability in justhtml before 1.12.0 Mutation XSS via Raw Text Elements. 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 before 1.12.0 (versions <= 1.11.0) contains a mutation cross-site scripting (mXSS) vulnerability in the serialization of raw-text elements such as <style> and <script>. When a DOM tree is processed by sanitize_dom() using a custom policy that keeps these elements, text nodes inside them are serialized literally without escaping, allowing attacker-controlled text containing the matching closing tag sequence to break out of the raw-text context and inject arbitrary HTML into the serialized output. The default sanitization policy is not affected because it drops the contents of style and script.

Quoted source text, attributed separately from HOL analysis.