iCalendar has ICS injection via unsanitized URI property values_CVE-2026-33635

{
    "lastseen": "",
    "description": "iCalendar is a Ruby library for dealing with iCalendar files in the iCalendar format defined by RFC-5545. Starting in version 2.0.0 and prior to version 2.12.2, .ics serialization does not properly sanitize URI property values, enabling ICS injection through attacker-controlled input, adding arbitrary calendar lines to the output. `Icalendar::Values::Uri` falls back to the raw input string when `URI.parse` fails and later serializes it with `value.to_s` without removing or escaping `\\r` or `\\n` characters. That value is embedded directly into the final ICS line by the normal serializer, so a payload containing CRLF can terminate the original property and create a new ICS property or component. (It looks like you can inject via url, source, image, organizer, attach, attendee, conference, tzurl because of this). Applications that generate `.ics` files from partially untrusted metadata are impacted. As a result, downstream calendar clients or importers may process attacker-supplied content as if it were legitimate event data, such as added attendees, modified URLs, alarms, or other calendar fields. Version 2.12.2 contains a patch for the issue.",
    "published": "2026-03-26T20:30:43.696Z",
    "modified": "2026-03-30T11:33:48.950Z",
    "type": "cve",
    "title": "iCalendar has ICS injection via unsanitized URI property values",
    "source": "GitHub_M",
    "references": "https://github.com/icalendar/icalendar/security/advisories/GHSA-pv9c-9mfh-hvxq\nhttps://github.com/icalendar/icalendar/commit/b8d23b490363ee5fffaec1d269a8618a912ca265\nhttps://github.com/rubysec/ruby-advisory-db/blob/master/gems/icalendar/CVE-2026-33635.yml",
    "id": "CVE-2026-33635",
    "bulletinFamily": "",
    "cwe": [
        "CWE-93"
    ],
    "cvelist": null,
    "sourceData": "icalendar icalendar >= 2.0.0, < 2.12.2",
    "sourceHref": "",
    "cvss": {
        "score": 4.3,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
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            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "icalendar",
    "version": ">= 2.0.0, < 2.12.2",
    "vendor": "icalendar",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}