CVE-2026-77399
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.
Does this matter?
Lower severity and a low EPSS score (0.31%). Track it; it rarely justifies an emergency change on its own.
Description
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
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.31% probability · 24th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-400, CWE-834
- Source
- security-advisories@github.com
EPSS moved from 0.5% on 23 September 2026 to 0.3% on 26 October 2026.
References
- 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.