{"id":"CVE-2026-77399","summary":"icalendar: Denial of service via unbounded VALARM REPEAT expansion","details":"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.","aliases":["GHSA-qjcq-q7h7-r74v"],"modified":"2026-09-25T03:30:25.486879523Z","published":"2026-09-22T18:58:56.647Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-400","CWE-834"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77399.json"},"references":[{"type":"WEB","url":"https://github.com/collective/icalendar/releases/tag/v7.2.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77399.json"},{"type":"ADVISORY","url":"https://github.com/collective/icalendar/security/advisories/GHSA-qjcq-q7h7-r74v"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77399"},{"type":"FIX","url":"https://github.com/collective/icalendar/commit/157f85137c65565a308bbcf4fdcc7d8ebce01267"},{"type":"FIX","url":"https://github.com/collective/icalendar/commit/cddd37226adbc52cca52a399f61d38a378221219"},{"type":"FIX","url":"https://github.com/collective/icalendar/pull/1571"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/collective/icalendar","events":[{"introduced":"a492d69437892bca718658487b18c632a71371c4"},{"fixed":"157f85137c65565a308bbcf4fdcc7d8ebce01267"},{"fixed":"cddd37226adbc52cca52a399f61d38a378221219"},{"fixed":"ad87bcf719fde8088a77c724bc2ae8f09545e0e4"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"6.1.0"},{"fixed":"7.2.2"}]}}],"versions":["v7.2.1","v7.2.0","v7.1.3","v7.1.2","v7.1.1","v7.1.0","v7.0.3","v7.0.2","v7.0.1","v7.0.0","v7.0.0a3","v7.0.0a2","v6.3.1","v7.0.0a1","v6.3.0","v6.2.0","v6.1.3","v6.1.2","v6.1.1","v6.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77399.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}