---
cve: "CVE-2026-55247"
severity: "CRITICAL"
cvss: 9.1
epss: "0.3%"
vendor: "plone"
kev: false
exploited: false
published: "2026-08-28 18:59:01"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-30T06:48:38+02:00"
---

# CVE-2026-55247

> 9.1 CRITICAL · 🧪 PoC

## Beschreibung

plone.app.event provides the event content type for Plone. Prior to versions 5.2.4 and 6.0.1, the iCalendar import in src/plone/app/event/ical/importer.py accepts insufficiently restricted calendar and event URLs, does not adequately bound downloaded bytes or imported events, and commits work per event. A logged-in editor can make the server request internal network resources or local calendar files, exhaust resources and take the site offline, and store a malicious event URL that executes script in another user's browser. The fix restricts accepted URLs, applies MAXIMUM_ICAL_IMPORT_SIZE_BYTES and MAXIMUM_ICAL_IMPORT_EVENTS limits, uses transaction savepoints, and validates event URLs. This issue is fixed in versions 5.2.4 and 6.0.1.

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **no**
  - Technical Impact: **partial**

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- 67343d3385073c618d37f3835e7575e010fa1ca7 (Commit)
- 0bbaa2f5d32625d5cb895089c7d974c775b36ce6 (Commit)

## Referenzen

- <https://github.com/plone/plone.app.event/security/advisories/GHSA-r82h-mqw3-fc56>
- <https://github.com/plone/plone.app.event/commit/1e3c83c15a24d1a789cdb012593505bc5620e28e>
- <https://github.com/plone/plone.app.event/commit/4de5eb3ea9e4f7f1781622e6d64fc086629d1437>
- <https://github.com/plone/plone.app.event/releases/tag/5.2.4>
- <https://github.com/plone/plone.app.event/releases/tag/6.0.1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-55247) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_