CVE-2026-5389 (GCVE-0-2026-5389)
Vulnerability from cvelistv5 – Published: 2026-08-23 13:34 – Updated: 2026-08-24 18:15
VLAI
EPSS
VEX
Title
justhtml before 1.13.0 XSS via code fence breakout
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.
Severity
6.1 (Medium)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-24 18:15 UTC
CWE
- CWE-80 - Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/EmilStenstrom/justhtml/securit… | vendor-advisory |
| https://www.vulncheck.com/advisories/justhtml-bef… | third-party-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| EmilStenstrom | justhtml |
Affected:
0 , < 1.13.0
(semver)
Unaffected: 1.13.0 (semver) |
guessed |
Date Public
2026-03-21 00:00
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