{ "document": { "category": "csaf_base", "csaf_version": "2.0", "distribution": { "tlp": { "label": "WHITE" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings." } ], "publisher": { "category": "coordinator", "contact_details": "cert@ncsc.nl", "name": "National Cyber Security Centre", "namespace": "https://www.ncsc.nl/" }, "title": "CVE-2026-33635", "tracking": { "current_release_date": "2026-03-30T19:38:32.611455Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-33635", "initial_release_date": "2026-03-25T00:40:33.324097Z", "revision_history": [ { "date": "2026-03-25T00:40:33.324097Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (31).| Product Identifiers created (30).| References created (2).| CWES updated (1)." }, { "date": "2026-03-25T00:40:45.467092Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-25T01:00:01.350486Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)." }, { "date": "2026-03-25T01:00:05.470689Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-03-26T21:27:38.034819Z", "number": "5", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)." }, { "date": "2026-03-26T21:27:44.435086Z", "number": "6", "summary": "NCSC Score updated." }, { "date": "2026-03-26T21:38:44.129005Z", "number": "7", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| References created (3).| CWES updated (1)." }, { "date": "2026-03-26T21:38:50.074493Z", "number": "8", "summary": "NCSC Score updated." }, { "date": "2026-03-27T20:56:38.829083Z", "number": "9", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-27T20:56:43.724523Z", "number": "10", "summary": "NCSC Score updated." }, { "date": "2026-03-28T07:57:45.247638Z", "number": "11", "summary": "References created (2)." }, { "date": "2026-03-28T08:10:38.877039Z", "number": "12", "summary": "References removed (2)." }, { "date": "2026-03-28T12:44:27.641180Z", "number": "13", "summary": "Source created.| CVE status created. (valid)| Description created for source.| Products created (2)." }, { "date": "2026-03-29T01:16:15.331581Z", "number": "14", "summary": "References created (2)." }, { "date": "2026-03-30T12:39:37.942655Z", "number": "15", "summary": "Unknown change." }, { "date": "2026-03-30T12:39:41.482659Z", "number": "16", "summary": "NCSC Score updated." } ], "status": "interim", "version": "16" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/2.0.0", "product": { "name": "vers:unknown/2.0.0", "product_id": "CSAFPID-5903995", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.0.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.0.1", "product": { "name": "vers:unknown/2.0.1", "product_id": "CSAFPID-5903996", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.0.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.1.0", "product": { "name": "vers:unknown/2.1.0", "product_id": "CSAFPID-5903997", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.1.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.1.1", "product": { "name": "vers:unknown/2.1.1", "product_id": "CSAFPID-5903998", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.1.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.1.2", "product": { "name": "vers:unknown/2.1.2", "product_id": "CSAFPID-5903999", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.1.2" } } }, { "category": "product_version_range", "name": "vers:unknown/2.10.0", "product": { "name": "vers:unknown/2.10.0", "product_id": "CSAFPID-5904000", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.10.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.10.1", "product": { "name": "vers:unknown/2.10.1", "product_id": "CSAFPID-5904001", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.10.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.10.2", "product": { "name": "vers:unknown/2.10.2", "product_id": "CSAFPID-5904002", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.10.2" } } }, { "category": "product_version_range", "name": "vers:unknown/2.10.3", "product": { "name": "vers:unknown/2.10.3", "product_id": "CSAFPID-5904003", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.10.3" } } }, { "category": "product_version_range", "name": "vers:unknown/2.11.0", "product": { "name": "vers:unknown/2.11.0", "product_id": "CSAFPID-5904004", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.11.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.11.1", "product": { "name": "vers:unknown/2.11.1", "product_id": "CSAFPID-5904005", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.11.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.11.2", "product": { "name": "vers:unknown/2.11.2", "product_id": "CSAFPID-5904006", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.11.2" } } }, { "category": "product_version_range", "name": "vers:unknown/2.12.0", "product": { "name": "vers:unknown/2.12.0", "product_id": "CSAFPID-5904007", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.12.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.12.1", "product": { "name": "vers:unknown/2.12.1", "product_id": "CSAFPID-5904008", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.12.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.2.0", "product": { "name": "vers:unknown/2.2.0", "product_id": "CSAFPID-5904009", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.2.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.2.1", "product": { "name": "vers:unknown/2.2.1", "product_id": "CSAFPID-5904010", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.2.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.2.2", "product": { "name": "vers:unknown/2.2.2", "product_id": "CSAFPID-5904011", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.2.2" } } }, { "category": "product_version_range", "name": "vers:unknown/2.3.0", "product": { "name": "vers:unknown/2.3.0", "product_id": "CSAFPID-5904012", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.3.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.4.0", "product": { "name": "vers:unknown/2.4.0", "product_id": "CSAFPID-5904013", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.4.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.4.1", "product": { "name": "vers:unknown/2.4.1", "product_id": "CSAFPID-5904014", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.4.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.5.0", "product": { "name": "vers:unknown/2.5.0", "product_id": "CSAFPID-5904015", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.5.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.5.1", "product": { "name": "vers:unknown/2.5.1", "product_id": "CSAFPID-5904016", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.5.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.5.2", "product": { "name": "vers:unknown/2.5.2", "product_id": "CSAFPID-5904017", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.5.2" } } }, { "category": "product_version_range", "name": "vers:unknown/2.5.3", "product": { "name": "vers:unknown/2.5.3", "product_id": "CSAFPID-5904018", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.5.3" } } }, { "category": "product_version_range", "name": "vers:unknown/2.6.0", "product": { "name": "vers:unknown/2.6.0", "product_id": "CSAFPID-5904019", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.6.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.6.1", "product": { "name": "vers:unknown/2.6.1", "product_id": "CSAFPID-5904020", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.6.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.7.0", "product": { "name": "vers:unknown/2.7.0", "product_id": "CSAFPID-5904021", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.7.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.7.1", "product": { "name": "vers:unknown/2.7.1", "product_id": "CSAFPID-5904022", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.7.1" } } }, { "category": "product_version_range", "name": "vers:unknown/2.8.0", "product": { "name": "vers:unknown/2.8.0", "product_id": "CSAFPID-5904023", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.8.0" } } }, { "category": "product_version_range", "name": "vers:unknown/2.9.0", "product": { "name": "vers:unknown/2.9.0", "product_id": "CSAFPID-5904024", "product_identification_helper": { "purl": "pkg:gem/icalendar@2.9.0" } } }, { "category": "product_version_range", "name": "vers:unknown/>=2.0.0|<2.12.2", "product": { "name": "vers:unknown/>=2.0.0|<2.12.2", "product_id": "CSAFPID-5904025" } } ], "category": "product_name", "name": "icalendar" } ], "category": "vendor", "name": "icalendar" }, { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-5958364" } } ], "category": "product_name", "name": "ruby-icalendar" } ], "category": "product_family", "name": "bookworm" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-5958365" } } ], "category": "product_name", "name": "ruby-icalendar" } ], "category": "product_family", "name": "bullseye" } ], "category": "vendor", "name": "debian" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-33635", "cwe": { "id": "CWE-93", "name": "Improper Neutralization of CRLF Sequences ('CRLF Injection')" }, "notes": [ { "category": "description", "text": "### Summary\n.ics serialization does not properly sanitize URI property values, enabling ICS injection through attacker-controlled input, adding arbitrary calendar lines to the output.\n\n### Details\n`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)\n\nRelevant code:\n- `lib/icalendar/values/uri.rb:16`\n\n### PoC\nRun the following with the library loaded:\n\n```ruby\nrequire \"icalendar/value\"\nrequire \"icalendar/values/uri\"\n\nv = Icalendar::Values::Uri.new(\"https://a.example/ok\\r\\nATTENDEE:mailto:evil@example.com\")\nputs v.to_ical(Icalendar::Values::Text)\n```\n\noutput:\n\n```text\n;VALUE=URI:https://a.example/ok\nATTENDEE:mailto:evil@example.com\n```\n\n### Impact\nApplications 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.\n\n## Fix\nReject raw CR and LF characters in `URI`-typed values before serialization, or escape/encode them so they cannot terminate the current ICS content line.", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/RubyGems%2FGHSA-pv9c-9mfh-hvxq.json?alt=media" }, { "category": "description", "text": "### Summary\n.ics serialization does not properly sanitize URI property values, enabling ICS injection through attacker-controlled input, adding arbitrary calendar lines to the output.\n\n### Details\n`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)\n\nRelevant code:\n- `lib/icalendar/values/uri.rb:16`\n\n### PoC\nRun the following with the library loaded:\n\n```ruby\nrequire \"icalendar/value\"\nrequire \"icalendar/values/uri\"\n\nv = Icalendar::Values::Uri.new(\"https://a.example/ok\\r\\nATTENDEE:mailto:evil@example.com\")\nputs v.to_ical(Icalendar::Values::Text)\n```\n\noutput:\n\n```text\n;VALUE=URI:https://a.example/ok\nATTENDEE:mailto:evil@example.com\n```\n\n### Impact\nApplications 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.\n\n## Fix\nReject raw CR and LF characters in `URI`-typed values before serialization, or escape/encode them so they cannot terminate the current ICS content line.", "title": "github - https://api.github.com/advisories/GHSA-pv9c-9mfh-hvxq" }, { "category": "description", "text": "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.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33635" }, { "category": "description", "text": "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.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33635.json" }, { "category": "description", "text": "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.", "title": "debian - https://security-tracker.debian.org/tracker/CVE-2026-33635" }, { "category": "other", "text": "0.00028", "title": "EPSS" }, { "category": "other", "text": "3.8", "title": "NCSC Score" }, { "category": "other", "text": "There is cwe data available from source Nvd, The value of the most recent EPSS score, The CVSS vector string contains AV:N (Attack Vector: Network)", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5903995", "CSAFPID-5903996", "CSAFPID-5903997", "CSAFPID-5903998", "CSAFPID-5903999", "CSAFPID-5904000", "CSAFPID-5904001", "CSAFPID-5904002", "CSAFPID-5904003", "CSAFPID-5904004", "CSAFPID-5904005", "CSAFPID-5904006", "CSAFPID-5904007", "CSAFPID-5904008", "CSAFPID-5904009", "CSAFPID-5904010", "CSAFPID-5904011", "CSAFPID-5904012", "CSAFPID-5904013", "CSAFPID-5904014", "CSAFPID-5904015", "CSAFPID-5904016", "CSAFPID-5904017", "CSAFPID-5904018", "CSAFPID-5904019", "CSAFPID-5904020", "CSAFPID-5904021", "CSAFPID-5904022", "CSAFPID-5904023", "CSAFPID-5904024", "CSAFPID-5904025", "CSAFPID-5958364", "CSAFPID-5958365" ] }, "references": [ { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/RubyGems%2FGHSA-pv9c-9mfh-hvxq.json?alt=media" }, { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-pv9c-9mfh-hvxq" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33635" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33635.json" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - debian", "url": "https://security-tracker.debian.org/tracker/CVE-2026-33635" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://github.com/icalendar/icalendar/security/advisories/GHSA-pv9c-9mfh-hvxq" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://github.com/icalendar/icalendar/commit/b8d23b490363ee5fffaec1d269a8618a912ca265" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-pv9c-9mfh-hvxq" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/icalendar/CVE-2026-33635.yml" }, { "category": "external", "summary": "Reference - github", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33635" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N", "baseScore": 4.3, "baseSeverity": "MEDIUM" }, "products": [ "CSAFPID-5903995", "CSAFPID-5903996", "CSAFPID-5903997", "CSAFPID-5903998", "CSAFPID-5903999", "CSAFPID-5904000", "CSAFPID-5904001", "CSAFPID-5904002", "CSAFPID-5904003", "CSAFPID-5904004", "CSAFPID-5904005", "CSAFPID-5904006", "CSAFPID-5904007", "CSAFPID-5904008", "CSAFPID-5904009", "CSAFPID-5904010", "CSAFPID-5904011", "CSAFPID-5904012", "CSAFPID-5904013", "CSAFPID-5904014", "CSAFPID-5904015", "CSAFPID-5904016", "CSAFPID-5904017", "CSAFPID-5904018", "CSAFPID-5904019", "CSAFPID-5904020", "CSAFPID-5904021", "CSAFPID-5904022", "CSAFPID-5904023", "CSAFPID-5904024", "CSAFPID-5904025", "CSAFPID-5958364", "CSAFPID-5958365" ] } ], "title": "CVE-2026-33635" } ] }