{"id":"CVE-2026-77399","state":"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.","publishedAt":"2026-09-22T18:58:56.647Z","updatedAt":"2026-09-23T14:36:47.671Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["collective icalendar"],"affected":[{"vendor":"collective","product":"icalendar","versions":[{"version":">= 6.1.0, < 7.2.2","status":"affected"}]}],"references":["https://github.com/collective/icalendar/security/advisories/GHSA-qjcq-q7h7-r74v","https://github.com/collective/icalendar/pull/1571","https://github.com/collective/icalendar/commit/157f85137c65565a308bbcf4fdcc7d8ebce01267","https://github.com/collective/icalendar/commit/cddd37226adbc52cca52a399f61d38a378221219","https://github.com/collective/icalendar/releases/tag/v7.2.2"],"weaknesses":["CWE-400","CWE-834"],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/77xxx/CVE-2026-77399.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-77399","state":"PUBLISHED","datePublished":"2026-09-22T18:58:56.647Z","dateUpdated":"2026-09-23T14:36:47.671Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-20T19:55:27.023Z"},"containers":{"cna":{"title":"icalendar: Denial of service via unbounded VALARM REPEAT expansion","descriptions":[{"lang":"en","value":"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":[{"vendor":"collective","product":"icalendar","versions":[{"version":">= 6.1.0, < 7.2.2","status":"affected"}]}],"references":[{"url":"https://github.com/collective/icalendar/security/advisories/GHSA-qjcq-q7h7-r74v","name":"https://github.com/collective/icalendar/security/advisories/GHSA-qjcq-q7h7-r74v","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/collective/icalendar/pull/1571","name":"https://github.com/collective/icalendar/pull/1571","tags":["x_refsource_MISC"]},{"url":"https://github.com/collective/icalendar/commit/157f85137c65565a308bbcf4fdcc7d8ebce01267","name":"https://github.com/collective/icalendar/commit/157f85137c65565a308bbcf4fdcc7d8ebce01267","tags":["x_refsource_MISC"]},{"url":"https://github.com/collective/icalendar/commit/cddd37226adbc52cca52a399f61d38a378221219","name":"https://github.com/collective/icalendar/commit/cddd37226adbc52cca52a399f61d38a378221219","tags":["x_refsource_MISC"]},{"url":"https://github.com/collective/icalendar/releases/tag/v7.2.2","name":"https://github.com/collective/icalendar/releases/tag/v7.2.2","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-834","lang":"en","description":"CWE-834: Excessive Iteration","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-22T18:58:56.647Z"},"source":{"advisory":"GHSA-qjcq-q7h7-r74v","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-23T14:10:14.416349Z","id":"CVE-2026-77399","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-23T14:36:47.671Z"}}]}}}