> CVE-2026-33635 [MEDIUM]

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PUBLISHED
2026-03-26 21:17
MODIFIED
2026-03-26 21:17
CVSS_SCORE V3
4.3
EPSS (Prob. Exploit)
0.39%
Top 68.3%
DATA SOURCES:
NVD 🔗 2026-03-26 CWE MITRE 🔗 2026-11-01 FIRST EPSS 🔗 2026-10-25 GITHUB 🔗 2026-10-28

> 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.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
EXPLOITABILITY
2.8
IMPACT
1.4

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Network (N)
Exploit possible à distance via réseau (HTTP, API, etc.)
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
Required (R)
Nécessite une action utilisateur (clic lien, ouverture fichier, etc.)
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
None (N)
Aucune divulgation d'informations
I (Impact Intégrité)
Integrity Impact
Low (L)
Modification limitée des données possible
A (Impact Disponibilité)
Availability Impact
None (N)
Aucune interruption de service

> RÉSUMÉ DES IMPACTS

Confidentialité
None
Aucune divulgation d'informations
Intégrité
Low
Modification limitée des données possible
Disponibilité
None
Aucune interruption de service

> WEAKNESSES

CWE-93

> CWE DETAILED DESCRIPTIONS

CWE-93: Improper Neutralization of CRLF Sequences - The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.

> GITHUB SECURITY ADVISORY

GHSA-pv9c-9mfh-hvxq MODERATE

iCalendar has ICS injection via unsanitized URI property values

AFFECTED PACKAGES:
RUBYGEMS / icalendar
>= 2.0.0, < 2.12.2
Fixed in: 2.12.2

> HISTORIQUE DES MODIFICATIONS

Première apparition
26/03/2026 21:17
Source: NVD
📊 ENRICHISSEMENT 01/11/2026 06:59
CWE
Champ modifié: Description CWE
Ancienne valeur:
CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection') - The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutr...
Nouvelle valeur:
CWE-93: Improper Neutralization of CRLF Sequences - The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectl...
📊 ENRICHISSEMENT 01/04/2026 06:02
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection') - The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutr...
Total des modifications: 2 Dernière mise à jour: 1 week ago

> REFERENCES

https://github.com/icalendar/icalendar/commit/b8d23b490363ee5fffaec1d269a8618a91...
https://github.com/icalendar/icalendar/security/advisories/GHSA-pv9c-9mfh-hvxq
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/icalendar/CVE-2026-...
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