CVE-2026-77399
mediumicalendar is an RFC 5545 compatible parser and generator of iCalendar files for Python.
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:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://github.com/collective/icalendar/commit/157f85137c65565a308bbcf4fdcc7d8ebce01267 security-advisories@github.com
- https://github.com/collective/icalendar/commit/cddd37226adbc52cca52a399f61d38a378221219 security-advisories@github.com
- https://github.com/collective/icalendar/pull/1571 security-advisories@github.com
- https://github.com/collective/icalendar/releases/tag/v7.2.2 security-advisories@github.com
- https://github.com/collective/icalendar/security/advisories/GHSA-qjcq-q7h7-r74v security-advisories@github.com