CVE-2026-5389
5.1
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
Summary
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 Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| EmilStenstrom | justhtml | 0 < 1.13.0 | affected |
| EmilStenstrom | justhtml | 1.13.0 | unaffected |
Weaknesses
- CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
References
- https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-5vp3-3cg6-2rq3
- https://www.vulncheck.com/advisories/justhtml-before-xss-via-code-fence-breakout
Feedback
Was this page helpful?
Glad to hear it! Please tell us how we can improve.
Sorry to hear that. Please tell us how we can improve.