CVE-2026-77088

MEDIUM 6.1

justhtml 0.9.0 through 1.21.0 Cross-Site Scripting via code-span

CVSS Score

6.1

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-79
Vendor	emilstenstrom
Product	justhtml
Published	Aug 23, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Affected Versions

EmilStenstrom / justhtml

All versions affected

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-jf6w-2mvx-633j vulncheck.com: https://www.vulncheck.com/advisories/justhtml-through-cross-site-scripting-via-code-span

Credits

🔍 seankohjs 🔍 yueyueL