---
cve: "CVE-2026-71478"
severity: "MEDIUM"
cvss: 6.1
epss: "0.2%"
vendor: "thephpleague"
kev: false
exploited: false
published: "2026-08-06 20:30:32"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-23T09:54:37+02:00"
---

# CVE-2026-71478

> 6.1 MEDIUM · 🧪 PoC

## Beschreibung

league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Erforderlich | good |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Gering | warn |
| I Integrität | Gering | warn |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- 493a5aa7d65754b73846006eaff9c2c4431a8e2c (Commit)
- 5703d83ba3da3b2e356a5fedc848ed6d8ffb6529 (Commit)

## Referenzen

- <https://github.com/thephpleague/commonmark/security/advisories/GHSA-29pj-957v-52mc>
- <https://github.com/thephpleague/commonmark/commit/493a5aa7d65754b73846006eaff9c2c4431a8e2c>
- <https://github.com/thephpleague/commonmark/releases/tag/2.9.0>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-71478) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_