Answer in brief
CVE-2026-5389 records a Medium severity (CVSS 6.1) vulnerability in justhtml before 1.13.0 XSS via code fence breakout. The current sources do not mark it as known exploited. The current feed maps EmilStenstrom/justhtml (generic), justhtml (pypi). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.1. 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.
The current feed maps EmilStenstrom/justhtml (generic), justhtml (pypi). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| EmilStenstrom/justhtmlgeneric | >=0 <1.13.0 | 1.13.0 |
| justhtmlpypi | >=0 <1.13.0 | 1.13.0 |
Published upstream
Aug 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 26, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 23, 2026
justhtml versions before 1.13.0 contain a cross-site scripting vulnerability in the to_markdown() function when serializing attacker-controlled pre content. Attackers can place backticks inside sanitized pre elements to break out of fixed-length code fences, allowing raw HTML to execute when the generated Markdown is rendered by CommonMark or GFM-style renderers.
Quoted source text, attributed separately from HOL analysis.