---
cve: "CVE-2026-59711"
severity: "MEDIUM"
cvss: 5.3
epss: "19%"
vendor: "showdown"
kev: false
exploited: false
published: "2026-07-06 21:16:58"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-11T08:22:47+02:00"
---

# CVE-2026-59711

> 5.3 MEDIUM · 🧪 PoC

## Beschreibung

showdown contains a cross-site scripting vulnerability in metadata title handling that allows attackers to inject arbitrary HTML and JavaScript. When completeHTMLDocument option is enabled, unescaped less-than and greater-than characters in markdown frontmatter metadata are inserted directly into HTML title tags, enabling attackers to break out of the title context and execute malicious scripts in the rendered page.

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |

## Referenzen

- <https://github.com/showdownjs/showdown/issues/1047>
- <https://github.com/showdownjs/showdown>
- <https://www.vulncheck.com/advisories/showdown-cross-site-scripting-via-unescaped-metadata-title-in-completehtmldocument>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-59711) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_