CVE-2026-77399
icalendar is an RFC 5545 compatible parser and generator of iCalendar files for Python.
Impact
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.
Affected packages
This record carries no package version data, so it cannot be matched against a dependency list automatically. Read the advisory and compare your version by hand.
Weakness classification
References
- NVD record
- CVE.org record
- https://github.com/collective/icalendar/commit/157f85137c65565a308bbcf4fdcc7d8ebce01267
- https://github.com/collective/icalendar/commit/cddd37226adbc52cca52a399f61d38a378221219
- https://github.com/collective/icalendar/pull/1571
- https://github.com/collective/icalendar/releases/tag/v7.2.2
- https://github.com/collective/icalendar/security/advisories/GHSA-qjcq-q7h7-r74v