# CVE-2026-5389

## Summary

- **CVE ID:** CVE-2026-5389
- **Severity:** MEDIUM
- **CVSS Score:** 6.1 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N)
- **CWE:** CWE-80
- **Published:** Aug 23, 2026
- **Last Modified:** Aug 24, 2026

## Description

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.

## Affected Products

- EmilStenstrom — justhtml (0)
- EmilStenstrom — justhtml (1.13.0)

## References

- [CNA](https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-5vp3-3cg6-2rq3)
- [CNA](https://www.vulncheck.com/advisories/justhtml-before-xss-via-code-fence-breakout)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.19%
- **EPSS Percentile:** 8.5

---
_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._