---
cve: "CVE-2026-86435"
severity: "HIGH"
cvss: 8.7
epss: "0.3%"
vendor: "thephpleague"
kev: false
exploited: false
published: "2026-09-07 12:53:53"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-22T21:52:13+02:00"
---

# CVE-2026-86435

> 8.7 HIGH · 🧪 PoC

## Beschreibung

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessive memory and CPU to exhaust server resources.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
```

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

## Referenzen

- <https://github.com/thephpleague/commonmark/security/advisories/GHSA-jfm3-95jq-q3rf>
- <https://www.vulncheck.com/advisories/commonmark-1.5.0-before-2.8.4-denial-of-service-via-footnote>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-86435) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_