justhtml 0.9.0 through 1.21.0 Cross-Site Scripting via code-span
Priority LOW 30CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-79.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00263 18th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| EmilStenstrom | justhtml | 0.9.0 – 1.21.0 | — | No fix listed | CNA |
- justhtml VendorEmilStenstrom Affected 0.9.0 – 1.21.0 Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-77088
- 2026-10-03 Alias added: GHSA-3r4x-v5v7-fm2r
References
More EmilStenstrom vulnerabilities
- TI-2026-07422 justhtml before 1.12.0 Sanitizer Bypass via Markdown CVSS 4.0CRITICAL 9.3
- TI-2026-08560 justhtml before 1.10.0 Denial of Service via deeply nested HTML CVSS 4.0HIGH 8.7
- TI-2026-52557 justhtml before 3.11.0 XSS via selectedcontent projection CVSS 4.0MEDIUM 5.1
- TI-2026-04717 justhtml before 1.13.0 XSS via code fence breakout CVSS 4.0MEDIUM 5.1
- TI-2026-06871 justhtml before 1.16.0 Multiple Security Issues via Sanitization CVSS 4.0CRITICAL 9.3
- TI-2026-04716 justhtml before 1.15.0 Multiple Security Issues CVSS 4.0CRITICAL 9.3
Sources
- CVE-2026-77088 · CVE Program
- CVE-2026-77088 · NVD
- FIRST EPSS
- GHSA-3r4x-v5v7-fm2r · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences