{"id":"CVE-2026-77399","aliases":["DEBIAN-CVE-2026-77399","EUVD-2026-84800","GHSA-qjcq-q7h7-r74v","UBUNTU-CVE-2026-77399"],"status":"published","title":"icalendar: Denial of service via unbounded VALARM REPEAT expansion","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.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00312,"percentile":0.24347,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400","CWE-834"],"published":"2026-09-22T18:58:56Z","modified":"2026-10-28T02:30:44Z","fixes":[{"ecosystem":"Debian:14","package":"python-icalendar","fixed_in":["7.3.0-1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:14","package":"python-icalendar","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.3.0-1"}]}],"versions":["6.0.1-2","6.0.1-3","6.3.1-1","6.3.1-2"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"python-icalendar","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.8-1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"python-icalendar","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.8-2","3.11.7-3","4.0.0-1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"python-icalendar","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.0.3-3","4.0.3-4"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"python-icalendar","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.0.3-4"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"python-icalendar","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.0.7-1","5.0.11-1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"python-icalendar","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.3.1-2"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"python-icalendar","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.0.1-3","6.3.1-1","6.3.1-2"]}],"products":[{"vendor":"collective","product":"icalendar"},{"vendor":"icalendar","product":"icalendar"}],"references":[{"url":"https://github.com/collective/icalendar/security/advisories/GHSA-qjcq-q7h7-r74v","tags":["x_refsource_CONFIRM","advisory","report"]},{"url":"https://github.com/collective/icalendar/pull/1571","tags":["x_refsource_MISC","fix","report"]},{"url":"https://github.com/collective/icalendar/commit/157f85137c65565a308bbcf4fdcc7d8ebce01267","tags":["x_refsource_MISC","fix","report"]},{"url":"https://github.com/collective/icalendar/commit/cddd37226adbc52cca52a399f61d38a378221219","tags":["x_refsource_MISC","fix","report"]},{"url":"https://github.com/collective/icalendar/releases/tag/v7.2.2","tags":["x_refsource_MISC","web","report"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77399.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77399","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-77399","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-77399","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-77399","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-77399","title":"icalendar: Denial of service via unbounded VALARM REPEAT expansion","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.","status":"published","published":"2026-09-22T18:58:56.647Z","modified":"2026-09-23T14:36:47.671Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-400","CWE-834"],"updated_at":"2026-11-02T14:20:15.712761Z"}],"euvd":[{"id":"EUVD-2026-84800","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.","status":"published","published":"2026-09-22T18:58:56Z","modified":"2026-09-23T14:36:47Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T17:28:00.949397Z"}],"nvd":[{"id":"CVE-2026-77399","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.","status":"published","published":"2026-09-22T19:16:51.443Z","modified":"2026-09-23T18:12:04.247Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-400","CWE-834"],"updated_at":"2026-11-02T14:12:50.703874Z"}],"osv":[{"id":"CVE-2026-77399","title":"icalendar: Denial of service via unbounded VALARM REPEAT expansion","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.","status":"published","published":"2026-09-22T18:58:56.647Z","modified":"2026-10-28T02:30:44.600244126Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-400","CWE-834"],"updated_at":"2026-11-02T15:45:17.102988Z"},{"id":"DEBIAN-CVE-2026-77399","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.","status":"published","published":"2026-09-22T19:16:51.443Z","modified":"2026-10-09T17:00:11.482092814Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:46:03.502256Z"},{"id":"UBUNTU-CVE-2026-77399","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.","status":"published","published":"2026-09-22T19:16:00Z","modified":"2026-10-17T13:01:07.839488067Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T16:57:18.015985Z"}]}}