CVE-2026-77399 (GCVE-0-2026-77399)

Vulnerability from cvelistv5 – Published: 2026-09-22 18:58 – Updated: 2026-09-23 14:36
VLAI
Title
icalendar: Denial of service via unbounded VALARM REPEAT expansion
Summary
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.
Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-23 14:10 UTC
CWE
  • CWE-400 - Uncontrolled Resource Consumption
  • CWE-834 - Excessive Iteration
Assigner
References
Impacted products
Vendor Product Version CPE status
collective icalendar Affected: >= 6.1.0, < 7.2.2
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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