{
    "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"
                }
            }
        ]
    }
}