---
cve: "CVE-2026-77399"
severity: "MEDIUM"
cvss: 6.5
epss: "0.5%"
vendor: "collective"
kev: false
exploited: false
published: "2026-09-22 19:16:51"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-26T16:03:13+02:00"
---

# CVE-2026-77399

> 6.5 MEDIUM · 🧪 PoC

## Beschreibung

icalendar is an RFC 5545 compatible parser and generator of iCalendar files for Python. From 6.1.0 until 7.2.2, vInt.from_ical accepts an attacker-controlled VALARM REPEAT value and applications that request alarm times can eagerly expand it without an application-level limit. Alarms.times and Alarms.active reach the unbounded expansion in versions starting with 6.1.0, while Alarm.triggers adds a second affected path starting with 7.0.0. Parsing alone does not trigger the issue, but accessing these properties can consume excessive CPU time and heap memory and terminate or stall a service. This issue is fixed in version 7.2.2.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- 157f85137c65565a308bbcf4fdcc7d8ebce01267 (Commit)
- cddd37226adbc52cca52a399f61d38a378221219 (Commit)

## Referenzen

- <https://github.com/collective/icalendar/security/advisories/GHSA-qjcq-q7h7-r74v>
- <https://github.com/collective/icalendar/pull/1571>
- <https://github.com/collective/icalendar/commit/157f85137c65565a308bbcf4fdcc7d8ebce01267>
- <https://github.com/collective/icalendar/commit/cddd37226adbc52cca52a399f61d38a378221219>
- <https://github.com/collective/icalendar/releases/tag/v7.2.2>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-77399) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_