CVE-2026-77088
justhtml 0.9.0 through 1.21.0 Cross-Site Scripting via code-span
- State
- Published
- Severity
- 5.3 Medium
- Published
- Aug 23, 2026
- Updated
- Aug 29, 2026
- Reserved
- Aug 20, 2026
Description
justhtml versions 0.9.0 through 1.21.0 contain a cross-site scripting vulnerability in to_markdown() where inline code spans fail to account for blank lines as block boundaries. Attackers can inject blank lines into code or pre element text to break the inline span, causing sanitized HTML to be emitted unescaped and re-parsed as live Markdown by compliant renderers.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.3 Medium | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N | VulnCheck |
| 3.1 | 6.1 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N | VulnCheck |
Weaknesses
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Products
| Product | Versions |
|---|---|
justhtmlEmilStenstrom |
|
References
- GitHub Security Advisory (GHSA-jf6w-2mvx-633j)vendor-advisory
- VulnCheck Advisory: justhtml 0.9.0 through 1.21.0 Cross-Site Scripting via code-spanthird-party-advisory
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