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| Vulnerability ID | VCID-t2g3-d1e3-5yg4 |
| Aliases |
CVE-2026-33635
GHSA-pv9c-9mfh-hvxq |
| Summary | 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. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 6.2 |
| Risk | 3.1 |
| Affected and Fixed Packages | Package Details |
| Reference id | Reference type | URL |
|---|---|---|
| https://api.first.org/data/v1/epss?cve=CVE-2026-33635 | ||
| https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-33635 | ||
| https://github.com/icalendar/icalendar | ||
| https://nvd.nist.gov/vuln/detail/CVE-2026-33635 | ||
| b8d23b490363ee5fffaec1d269a8618a912ca265 | https://github.com/icalendar/icalendar/commit/b8d23b490363ee5fffaec1d269a8618a912ca265 | |
| CVE-2026-33635.yml | https://github.com/rubysec/ruby-advisory-db/blob/master/gems/icalendar/CVE-2026-33635.yml | |
| GHSA-pv9c-9mfh-hvxq | https://github.com/advisories/GHSA-pv9c-9mfh-hvxq | |
| GHSA-pv9c-9mfh-hvxq | https://github.com/icalendar/icalendar/security/advisories/GHSA-pv9c-9mfh-hvxq |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
| Percentile | 0.16032 |
| EPSS Score | 0.0005 |
| Published At | June 11, 2026, 12:55 p.m. |
| Date | Actor | Action | Source | VulnerableCode Version |
|---|---|---|---|---|
| 2026-06-11T16:49:35.547332+00:00 | Vulnrichment | Import | https://github.com/cisagov/vulnrichment/blob/develop/2026/33xxx/CVE-2026-33635.json | 38.6.0 |