{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55099","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-06-16T14:41:54.579Z","datePublished":"2026-08-25T19:27:02.236Z","dateUpdated":"2026-08-26T15:05:26.062Z"},"containers":{"cna":{"title":"icalendar: Algorithmic Complexity in Equality","problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-407","lang":"en","description":"CWE-407: Inefficient Algorithmic Complexity","type":"CWE"}]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"references":[{"name":"https://github.com/collective/icalendar/security/advisories/GHSA-cv84-9p8j-fj68","tags":["x_refsource_CONFIRM"],"url":"https://github.com/collective/icalendar/security/advisories/GHSA-cv84-9p8j-fj68"},{"name":"https://github.com/collective/icalendar/commit/b6b2608ae3af6de40695b4e40f71847485aa0b49","tags":["x_refsource_MISC"],"url":"https://github.com/collective/icalendar/commit/b6b2608ae3af6de40695b4e40f71847485aa0b49"},{"name":"https://github.com/collective/icalendar/commit/cad40cd112c93fd142ec12cc5b37445a849b8a79","tags":["x_refsource_MISC"],"url":"https://github.com/collective/icalendar/commit/cad40cd112c93fd142ec12cc5b37445a849b8a79"},{"name":"https://github.com/collective/icalendar/releases/tag/v7.1.3","tags":["x_refsource_MISC"],"url":"https://github.com/collective/icalendar/releases/tag/v7.1.3"}],"affected":[{"vendor":"collective","product":"icalendar","versions":[{"version":">= 7.1.0, < 7.1.3","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-08-25T19:27:02.236Z"},"descriptions":[{"lang":"en","value":"icalendar is an RFC 5545 compatible parser and generator of iCalendar files for Python. From 7.1.0 until 7.1.3, the Component equality method in src/icalendar/cal/component.py compares nested subcomponents with two membership loops, and each membership test invokes the same method on child components, causing O(2^n) work relative to nesting depth. Component.from_ical accepts arbitrarily nested BEGIN:VEVENT blocks without a depth limit, so an attacker can submit a sub-kilobyte .ics file containing equal nested subtrees and trigger the cost when an application performs equality, inequality, membership, deduplication, test-assertion, round-trip, or normalization comparisons. Parsing alone does not trigger the issue, and comparisons that differ early short-circuit, but a few hundred bytes can pin a CPU core for minutes or indefinitely, causing denial of service in calendar sync or import endpoints, invite processing, and other comparison paths. This issue is fixed in version 7.1.3."}],"source":{"advisory":"GHSA-cv84-9p8j-fj68","discovery":"UNKNOWN"}},"adp":[{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/06/23/8"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2026-08-25T20:10:56.453Z"}},{"references":[{"url":"https://github.com/collective/icalendar/security/advisories/GHSA-cv84-9p8j-fj68","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-26T15:05:19.449076Z","id":"CVE-2026-55099","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-08-26T15:05:26.062Z"}}]}}